Luis has 5-cent coins and 10-cent coins. The total value of all his coins is $13. 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¢
$13 = 13 x 100 = 1300¢
Luis 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 = 1300
15 u = 1300 - 40
15 u = 1260
1 u = 1260 ÷ 15 = 84
Total number of coins
= 1 u + (1 u + 4)
= 2 u + 4
= 2 x 84 + 4
= 168 + 4
= 172
Answer(s): 172