1. Bills: A stack contains $400 worth of paper money consisting of $20 bills and $50 bills. There are 11 bills altogether. How many $20 bills and how many $50 bills are in the stack? 2. Mixing: You’re...

1. Bills: A stack contains $400 worth of paper money consisting of $20 bills and $50 bills. There are 11 bills altogether. How many $20 bills and how many $50 bills are in the stack?

2. Mixing: You’re mixing blue paint with yellow paint to get a total of 10 gallons of the mixture. You want to use 3 times as much yellow paint as blue paint. How many gallons of each should you use?