How many pennies and dimes are in the cup?

Question

Priam has pennies and dimes in a cup holder in his car. The total value of the coins is $4.21. The number of dimes is three less than four times the number of pennies. How many pennies and how many dimes are in the cup?

Answer 1

Let P represent pennies and D represent dimes. Each D is worth 10P.

Given D = 10P = 4P - 3

10(4P-3) + P = $4.21

(40P - 30) + P = 421 (number of P in $4.21)

41P = 451

P = 11

D = 4P - 3 = 44 - 3 = 41.

There are 41 D and 11 P.

Since each D = 10P, the total in terms of P = 410 + 11 = 421 = $4.21