Help with homework:Math

[TJ10]

My mind=blown.Lucky i have until monday to get this done.

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[Otis Da HousKat]

My mind=blown.Lucky i have until monday to get this done.

Do you understand how I set up the equations?

[TJ10]

I suck at it when its in a paragraph,Especally when its Distance and Cents.

[Menen]

Subject:Let Statements.
Dont tell me the answer,Just tell me the Let statements and the equation i have to solve.
I am clueless on these:

1.)Jacob finished a 42-mile race in 3 hours.He ran for average rate of 7 miles per hour and Biked for 22 miles per hour.How much time did he run and bike?(That isnt full question,Just important info)

2.)Jason Cooke bought 25 stamps,valued 37 and 39 cents.He paid with a 20 dollar bill.$10.45 change back.How many 37 and 39 cent stamps did he get?

Please help me.

What.

[TJ10]

What???
Edit:Will someone actually take this topic serious.
I dont want to stay after school.

[Otis Da HousKat]

1) Let x = time on foot, y = time on bike

x+y=3
7x+22y=42

The question is asking us to find the total time traveled on each method of movement. We are given two unknown variables, time spent on foot and time spent on bike, which have to total to three hours. This is where the first equation came from.

For the second equation we know the speeds he was traveling using each method. Remember x and y actually have the units of hours associated with them, so the equation looks like this before we cancel units:



I forgot to put it in the picture but the unit of miles can then be canceled out by division since it appears on both sides of the equation.

[Makingblah]

Otis beat me to it :C

I would use simultaneous equations.. But I'm not sure.

Let me try..

1.)Jacob finished a 42-mile race in 3 hours. He ran for average rate of 7 miles per hour and Biked for 22 miles per hour. How much time did he run and bike?

Let x be cycled, and y be ran.

x + y = 3
22x + 7y = 42

-7x + -7y = -21
22x + 7y = 42

15x = 21
x = 1.4

1.4 + y = 3
y = 3 - 1.4

y = 1.6

1.4 x 22 = 30.8
1.6 x 7 = 11.2

30.8 + 11.2 = 42.

The answer is Jacob ran for 1.4 hours and cycled for 1.6 hours.

There's the whole equation.

[TJ10]

Im not taking chances because we dont talk about y much in what were doing.
I remember a equation like this:3(x)+3(x+2)=Whatever
Thats a example of thats what were doing.
Now for the 2nd one.No clue.

For the first one.I was thinking like
3(x)+3(???)=42.
Because its Distance=rate * time

[Makingblah]

Im not taking chances because we dont talk about y much in what were doing.
I remember a equation like this:3(x)+3(x+2)=Whatever
Thats a example of thats what were doing.
Now for the 2nd one.No clue.

Ask your teacher to teach you the method of Simultaneous equations, because it's a stuffload easier to what you appear to be doing.

[Daedalus]

I'm studying the same thing as you in school, ololo :D
I would have solved it for you and showed you how, but Otis beat me to it.

[TJ10]

Sucks because my teacher isnt going to be here tomarrow and sub doesnt know anything because hes just in for the test were taking.
Wanna know what.Screw it,Ill take my chances with it.Now for the 2nd question.And then i got confused and took a risk.

[Makingblah]

Im not taking chances because we dont talk about y much in what were doing.
I remember a equation like this:3(x)+3(x+2)=Whatever
Thats a example of thats what were doing.
Now for the 2nd one.No clue.

For the first one.I was thinking like
3(x)+3(???)=42.
Because its Distance=rate * time

The triangle of DST.


Distance = Speed, but I'm sure you knew that.
               Time

[Otis Da HousKat]

I actually solve systems of equations like these all day. Except mine involve scary differentiations and trigonometric functions.