The sum of three numbers is 28. Twice the first number minus the second number is 2 less than the third number. The third number is the same as the second number minus 3 times the first number. Which system of equations that would help find the three numbers.

Henry paid a total of $360 for the dishwasher:  $20 + (10 x $34) = $20 + $340= $360

Therefore he paid $40 extra which we place over the original amount of the dishwasher:

Dividing 1 by 8 we get  .125 which, when changed to a percentage becomes 12.5%
Henry paid a yearly interest rate of 12.5%