Dylan has 5-cent coins and 10-cent coins. The total value of all his coins is $23. He has 20 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 + 20 |
2 u + 20 |
| Value |
5 |
10 |
|
| Total value |
5 u |
10 u + 200 |
15 u + 200 |
$1 = 100¢
$23 = 23 x 100 = 2300¢
Dylan has 20 more 10-cent coins than 5-cent coins.
Number of 5-cent coins = 1 u
Number of 10-cent coins = 1 u + 20
Total value of 5-cent coins
= 5 x 1 u
= 5 u
Total value of 10-cent coins
= 10 x (1 u + 20)
= 10 u + 200
Total value of the coins
= 5 u + 10 u + 200
= 15 u + 200
15 u + 200 = 2300
15 u = 2300 - 200
15 u = 2100
1 u = 2100 ÷ 15 = 140
Total number of coins
= 1 u + (1 u + 20)
= 2 u + 20
= 2 x 140 + 20
= 280 + 20
= 300
Answer(s): 300
