Use the distributive property to multiply the right side giving you 5x+15, if you subtract 5x from each side you get 8=15 which is never true, the equation has no solution.
Its 30% because if you take 103 put it in the calculator and divide by 100 you get 1.03 and multiply that time 30 you get 30.9 thats how you find percent
I think its B. correct me if wrong
