Ken has 5-cent coins and 10-cent coins. The total value of all his coins is $19. He has 19 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 + 19 |
2 u + 19 |
| Value |
5 |
10 |
|
| Total value |
5 u |
10 u + 190 |
15 u + 190 |
$1 = 100¢
$19 = 19 x 100 = 1900¢
Ken has 19 more 10-cent coins than 5-cent coins.
Number of 5-cent coins = 1 u
Number of 10-cent coins = 1 u + 19
Total value of 5-cent coins
= 5 x 1 u
= 5 u
Total value of 10-cent coins
= 10 x (1 u + 19)
= 10 u + 190
Total value of the coins
= 5 u + 10 u + 190
= 15 u + 190
15 u + 190 = 1900
15 u = 1900 - 190
15 u = 1710
1 u = 1710 ÷ 15 = 114
Total number of coins
= 1 u + (1 u + 19)
= 2 u + 19
= 2 x 114 + 19
= 228 + 19
= 247
Answer(s): 247
