Hey there. [Don't call yourself stupid- you're awesome! :)]
First, to determine if x = 8 is a solution, we need to substitute 'x' with 8.
Let's see what happens.
2(8) + 7 = 17; now, we need to subtract 7 from both sides and simplify 2(8).
16 = 10.
From the equation we are left with, x = 8 is not a solution.
I hope this helps! Have a great day. :)