simple equations ( math)
posted by vanessa .
Share $100 between Joseph and Peter so that Joseph has 3 times as much as Peter.

Let x = the amount of money that Peter has. Now try to set up the equation to solve for x.

sorry i don't understand

You want to solve for the amount of money that Peter has. So you let your variable equal that amount of money.
Now, you know that Peter's money + Joseph's money = $100.
Can you express the amount of money Joseph has in terms of x, the amount of money Peter has? 
so altogether the have $100. Joseph has 3 time more then Peter. would joseph have $75 and Peter have $15 ?

I believe you mean that Peter has $25, which would be correct.
Could you write the equation you used to solve that? 
ohyes sorry i meant that.
3/4 of 100 is 75
so the rest is 25 
Again, where is your variable (x) in the equation?
You should have an equation that looks like the following:
"Peter's money + Joseph's money = $100"
x + J(x) = $100
where J(x) is a (simple) function expressing Joseph's money in terms of x.
The reason I ask is not to make it hard now, but because you will encounter problems that cannot be solved mentally  multiple variable problems, for example. You will need to be able to set up an equation from the word problem. 
Oh. ook ... thank you for your help

alex spent 3/7 of his money. he give 1/4 of the reminder to his sister. he had $120
left. how much money did he have in the begining