You have to distribute the parentheses first. Since there is a negative sign in front of the parentheses, it counts as a negative 1. After you distribute you should get: -5+6x=20x+12, but that is not your final answer. After you add like terms: 17x=-17. Divide 17 on both sides: x=-1. X=-1 is your final answer.
No, she will still owe $9.30. $25.63 - $16.33= $9.30
First you do 3a^4(2b^6c^3)^2
=12a^4b^12c^6
$125.4 is the answer to #1
#2 im not sure how the 10% effects the problem. so i cant help you there