John has 5-cent coins and 50-cent coins. The total value of all his coins is $15. He has 19 less 5-cent coins than 50-cent coins. How many coins does he have altogether?
| |
5-cent |
50-cent |
Total |
| Number |
1 u |
1 u + 19 |
2 u + 19 |
| Value |
5 |
50 |
|
| Total value |
5 u |
50 u + 950 |
55 u + 950 |
$1 = 100¢
$15 = 15 x 100 = 1500¢
John has 19 more 50-cent coins than 5-cent coins.
Number of 5-cent coins = 1 u
Number of 50-cent coins = 1 u + 19
Total value of 5-cent coins
= 5 x 1 u
= 5 u
Total value of 50-cent coins
= 50 x (1 u + 19)
= 50 u + 950
Total value of the coins
= 5 u + 50 u + 950
= 55 u + 950
55 u + 950 = 1500
55 u = 1500 - 950
55 u = 550
1 u = 550 ÷ 55 = 10
Total number of coins
= 1 u + (1 u + 19)
= 2 u + 19
= 2 x 10 + 19
= 20 + 19
= 39
Answer(s): 39
