Japheth has 5-cent coins and 20-cent coins. The total value of all his coins is $40. He has 5 less 5-cent coins than 20-cent coins. How many coins does he have altogether?
| |
5-cent |
20-cent |
Total |
| Number |
1 u |
1 u + 5 |
2 u + 5 |
| Value |
5 |
20 |
|
| Total value |
5 u |
20 u + 100 |
25 u + 100 |
$1 = 100¢
$40 = 40 x 100 = 4000¢
Japheth has 5 more 20-cent coins than 5-cent coins.
Number of 5-cent coins = 1 u
Number of 20-cent coins = 1 u + 5
Total value of 5-cent coins
= 5 x 1 u
= 5 u
Total value of 20-cent coins
= 20 x (1 u + 5)
= 20 u + 100
Total value of the coins
= 5 u + 20 u + 100
= 25 u + 100
25 u + 100 = 4000
25 u = 4000 - 100
25 u = 3900
1 u = 3900 ÷ 25 = 156
Total number of coins
= 1 u + (1 u + 5)
= 2 u + 5
= 2 x 156 + 5
= 312 + 5
= 317
Answer(s): 317
