Question

Luis is saving money to purchase a new video game. He has a total of 30 coins consisting of nickels and dimes. The value of the coins is $2.20. Let n represent the number of nickels and let d represent the number of dimes. Which system of equations can be used to determine the number of nickels and the number of dimes Luis has?

A system of equations. n plus d equals 2.20. 10 n plus 5 d equals 30.
A system of equations. n plus d equals 2.20. 10 n plus 5 d equals 30.
A system of equations. n plus d equals 2.20. 0.5 n plus 0.1 d equals 30.
A system of equations. n plus d equals 30. 0.5 n plus 0.1 d equals 2.20.

Answer 1

The correct system is
n + d = 30
0.05n + 0.10d = 2.20

(This is equivalent to n + 2d = 44.) That matches choice D (n + d = 30 and the value equation). Solving gives d = 14 and n = 16.