Question

the value of y is directly proportional to the value of x. If y=35 when x=140, what is the value of y when x=70 ?

Answer 1

There’s two ways to complete this problem.
First way:
Let’s see if y can be multiplied by anything to get to x. We should divide y by x.
35/140
.25
So it looks like y will be 1/4 of x.
Since we know that, we can find the value of y using this equation.
.25x=y
.25•70
17.5
So the value of y when x=70 is 17.5
Second way:
As you can tell, they want us to find the value of y when x is half of what it was before.
140:35
70:y
All we have to do is divide 35 by 2 since that’s what we did to the other side.
35/2=17.5
When x is 70, y is 17.5.