Answer:
12 pennies
4 dimes
3 nickels
2 quarters
Step-by-step explanation:
Let p = pennies
d = dimes
q = quarters
n - nickels
d + n + p + q = 21
p = 4n
d = n + 1
q = n - 1
Now just subsitute them in and add the terms
(n + 1) + n + (4n) + (n - 1) = 21
7n = 21
Divide both sides by 7
7n/7 = 21/7
n = 3
Now use the new n to plug in the rest of the equations
p = 4(3) = 12
d = 3 + 1 = 4
q = 3 - 1 = 2
