You have a total of 21 coins, all nickels 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 nickels and let d = the number dimes.

n = number of nickels
d = number of dimes
1 nickel = 5 cents
1 dime = 10 cents
total number of 21 coins:
n + d = 21
Total value = $1.70
5n + 10 d = 170
Divide by 100
0.05n + 0.10 d = 1.70
Answer:
n + d = 21
0.05n + 0.10 d = 1.70