Question

Which equation can be used to solve the following word problem?

Answer 1

According to the statement, equation would be: 
0.10(n-6)+0.05n=2.10
0.10n - 0.60 + 0.05n = 2.10
0.15n = 2.70
n = 2.70/0.15
n = 18

So, in total he has 18 nickels

Answer 2

A is definitely the answer.