Lee has 5-cent coins and 10-cent coins. The total value of all his coins is $22. He has 13 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 + 13 |
2 u + 13 |
| Value |
5 |
10 |
|
| Total value |
5 u |
10 u + 130 |
15 u + 130 |
$1 = 100¢
$22 = 22 x 100 = 2200¢
Lee has 13 more 10-cent coins than 5-cent coins.
Number of 5-cent coins = 1 u
Number of 10-cent coins = 1 u + 13
Total value of 5-cent coins
= 5 x 1 u
= 5 u
Total value of 10-cent coins
= 10 x (1 u + 13)
= 10 u + 130
Total value of the coins
= 5 u + 10 u + 130
= 15 u + 130
15 u + 130 = 2200
15 u = 2200 - 130
15 u = 2070
1 u = 2070 ÷ 15 = 138
Total number of coins
= 1 u + (1 u + 13)
= 2 u + 13
= 2 x 138 + 13
= 276 + 13
= 289
Answer(s): 289
