So.. hmmm if we take "x" to be the 100% sale price before tax, $76 is really 9.5% of that
thus

solve for "x"
The person that factored the polynomial did one thing wrong -- they used minus signs when they should've used plus signs. We can figure this out because of the values of the quantities in the original trinomial. Since all of them are positive, we know that either there are two plus signs or that there is a minus and a plus sign with the value to the right of the plus sign being greater than the value to the right of the minus sign. But, that wouldn't work here, so the only thing wrong with this answer is that the plus signs should be minus signs.
So you would start with the square and do 18 times 18 which equals 324 then for the triangle it's base times height divided by two so 9 times 18 divided by 2 which equals 81 then you add the triangle plus the square and your final answer is
answer:405
When Sam is 13 his mother will be 39 which is 3 times as old as he is. So Sam's mother will be 3 times as old as Sam will be in 11 years. (Your answer is 11 years.)