Joe has 120 coins, all nickels and dimes. He has 20 more dimes then nickels.
a) Write a system of equations representing the scenario.
b) How many nickels and how many dimes does Joe have?
a) Let D be the number of dimes and N be the number of nickels
And we know that
D + N = 120
N + 20 = D
b) To solve this, sub the second equation in the first for "D" and we have
( N + 20 ) + N = 120 simplify
2N + 20 = 120 subtract 20 from each side
2N = 100 divide both sides by 2
N = 50 = the number of nickels
And N + 20 = D...so
50 + 20 = D = 70 = the number of dimes