You answer is 3 and here's why...
7x + 5 - 3x - 7 = 10
First you must collect like terms
And that gives us
4x - 2 = 10
Next you must simplify by removing additives
4x - 2 + 2 = 10 + 2
4x = 12
Now you must divide
4x/4 = 12/4
x = 3
Stephen is likely to qualify since his annual income is less than the median income of Texas.
I believe it is a triangular prism