Ethan has 5-cent coins and 10-cent coins. The total value of all his coins is $25. He has 4 less 5-cent coins than 10-cent coins. How many coins does he have altogether?
| |
5-cent |
10-cent |
Total |
| Number |
1 u |
1 u + 4 |
2 u + 4 |
| Value |
5 |
10 |
|
| Total value |
5 u |
10 u + 40 |
15 u + 40 |
$1 = 100¢
$25 = 25 x 100 = 2500¢
Ethan has 4 more 10-cent coins than 5-cent coins.
Number of 5-cent coins = 1 u
Number of 10-cent coins = 1 u + 4
Total value of 5-cent coins
= 5 x 1 u
= 5 u
Total value of 10-cent coins
= 10 x (1 u + 4)
= 10 u + 40
Total value of the coins
= 5 u + 10 u + 40
= 15 u + 40
15 u + 40 = 2500
15 u = 2500 - 40
15 u = 2460
1 u = 2460 ÷ 15 = 164
Total number of coins
= 1 u + (1 u + 4)
= 2 u + 4
= 2 x 164 + 4
= 328 + 4
= 332
Answer(s): 332
