Wesley has 10-cent coins and 20-cent coins. The total value of all his coins is $12. He has 6 less 10-cent coins than 20-cent coins. How many coins does he have altogether?
| |
10-cent |
20-cent |
Total |
| Number |
1 u |
1 u + 6 |
2 u + 6 |
| Value |
10 |
20 |
|
| Total value |
10 u |
20 u + 120 |
30 u + 120 |
$1 = 100¢
$12 = 12 x 100 = 1200¢
Wesley has 6 more 20-cent coins than 10-cent coins.
Number of 10-cent coins = 1 u
Number of 20-cent coins = 1 u + 6
Total value of 10-cent coins
= 10 x 1 u
= 10 u
Total value of 20-cent coins
= 20 x (1 u + 6)
= 20 u + 120
Total value of the coins
= 10 u + 20 u + 120
= 30 u + 120
30 u + 120 = 1200
30 u = 1200 - 120
30 u = 1080
1 u = 1080 ÷ 30 = 36
Total number of coins
= 1 u + (1 u + 6)
= 2 u + 6
= 2 x 36 + 6
= 72 + 6
= 78
Answer(s): 78
