Yuri buys one headlightand one tire kit. The headlight costs 3 times the cost of the tire kit. He pays for the otems with a $50 bill. How much change should Yuri recieve?

My daughter had this same question on her Math Homework. And on her paper it says that Yuri buys one headlight and one tire kit. The headlight costs 3 times the the cost of cost of the tire kit. He pays for the items with a $50.00 bill. His much change should Yuri receive? The answer is: 5*3=15+5.00=20.00-50.00=$30.00 So he would get $30.00 back in change