I assume you mean x squared in the first equation
Because both are equal to y, they are equal to each other so x + 5 = x^2 +3
If we then move everything over to one side, we get x^2 - x - 2 = 0
Then factorise it to (x-2)(x+1) = 0
And solve both parts separately
x + 1 = 0
x = -1
x-2 = 0
x = 2
Sub both values into the simplest equation in this case y=x+5
to get y = 4 and y = 7