Question

If if x+y=10, find the value of y when x=3

Answer 1

Let me help you,

for this question, you know what is x and you wanna find the y.
So the only thing you should do is to put 3 for x and solve the equation:
3 + y = 10 
y = 10 -3
y = 7 

Hava great one!

Answer 2

Hey, Hardq!
The problem already gave us x. So we plug it in.
3+y=10
We now want to make the variable by itself, so we subtract 3 to the other side.
y=10-3
Simple Math
y=7
I hope this helps;)