The product of a number and negative eight gives eight times the sum of that number and thirty-six

A girl has been getting her parents change every day for a year. She has dimes and half-dollars worth $50.00. If she has five times as many dimes as half-dollars, how many of each type of coin does she have?

Marco bought a new building for his company which was one tenth bigger than his current building. if his old building has x square feet, which expression represents how many more square feet the new building has?