I'm stuck on this word problem.

Question

Part of the proceeds from a garage sale was $410 worth of $10 bills and $20 bills. If there were 2 more $10 bills than $20 bills, find the number of each denomination.

Answer 1

x = No. of $10 bills; y = No. of $20 bills

x = y + 2

10x + 20y = 410; substitute for x: 10(y + 2) + 20y = 410

Use distribution rule: 10y + 20 + 20y = 410

30y = 390 y = 13 $20 bills ; x = 15 $10 bills

Check: 15(10) + 13(20) = 410