Solve using the five step method

Question

A bank employee is servicing the atm after a busy Friday night. She finds the machine contains only $20 bills and $10 bills and that there are thrice as many $20 bills remaining as there are $10 bills. If there is a total of $840.00 left in the machine, how many of the bills are twenties, and how many are tens? 

Answer 1

let x = the number of ten dollar bills

3x = the number of twenty dollar bills

 

10x + 20(3x) = 840

10x + 60x = 840

70x = 840

x = 12

 

There are 12 ten dollar bills and 3 * 12 = 36 twenty dollar bills in the ATM