Michael has 5-cent coins and 20-cent coins. The total value of all his coins is $36. He has 20 less 5-cent coins than 20-cent coins. How many coins does he have altogether?
| |
5-cent |
20-cent |
Total |
| Number |
1 u |
1 u + 20 |
2 u + 20 |
| Value |
5 |
20 |
|
| Total value |
5 u |
20 u + 400 |
25 u + 400 |
$1 = 100¢
$36 = 36 x 100 = 3600¢
Michael has 20 more 20-cent coins than 5-cent coins.
Number of 5-cent coins = 1 u
Number of 20-cent coins = 1 u + 20
Total value of 5-cent coins
= 5 x 1 u
= 5 u
Total value of 20-cent coins
= 20 x (1 u + 20)
= 20 u + 400
Total value of the coins
= 5 u + 20 u + 400
= 25 u + 400
25 u + 400 = 3600
25 u = 3600 - 400
25 u = 3200
1 u = 3200 ÷ 25 = 128
Total number of coins
= 1 u + (1 u + 20)
= 2 u + 20
= 2 x 128 + 20
= 256 + 20
= 276
Answer(s): 276
