You have a total of 21 coins, all nickles and dimes. the total value is $1.70 which of the following is the system of linear equations that represent this scenario? let n= the number of nickles and let d= the number of dimes.

You need one equation for the physical nickels and dimes, which total to 21:

n+d=21

Secondly, you need one equation for the numerical value of those nickels and dimes. We know nickels are worth $0.05 and dime are worth $0.10:

.05n+.1d=1.70

Think of it as five or above give it a shove. change the 5 or above to the right to a zero and add one to the number on the left.