Question

Sally has seven times as many dimes as nickels. Their value is $3.00. How many nickels does she have?



4 nickels

7 nickels

28 nickels

Answer 1

Call the number of nickels n. Then the number of dimes is 7n. The value of the amount of nickels is 0.05n because each nickel is worth $0.05. Thus the value of the amount of dimes is 0.10(7n) for the same reason.

so
0.05n+0.10*7n=3
0.05n+0.7n=3
0.75n=3
n=4

therefore, Sally has 4 nickels