Question

If (3,y) is a solution to the equation y=2x+4, what is the value of y?

Answer 1

Y=2X+4
Y=2(3)+4
Y=6+4
Y=10

Answer 2

Here, all you have to do is simply substitute (3) for the variable (x) in the equation. You can do this because all coordinates are of the form (x,y), and anything that takes the place of (x) in that form can be seen as equal to (x).
The working is shown below:
y = 2(3) + 4
y = 6 + 4
y = 10
As shown above, y = 10 when x = 3.