Question

What is the value of x in the equation x – y = 30, when y = 15?

Answer 1

`x-y=30 \ when \ y=15 \\ \\ x-15=30 \\ \\ x=30+15 \\ \\ x=45`

Answer 2

To find " X", you'll need subsitute "y" with 15 and solve the equation.

So, it would look like this:

x - y = 30
x - 15 = 30 (subsitute)
x - 15 + 15 = 30 + 15 (add on both sides of the = sign)
x = 45 (final solution)

Hope this helps!
:)