Ian has 20-cent coins and 50-cent coins. The total value of all his coins is $17. He has 13 less 20-cent coins than 50-cent coins. How many coins does he have altogether?
| |
20-cent |
50-cent |
Total |
| Number |
1 u |
1 u + 13 |
2 u + 13 |
| Value |
20 |
50 |
|
| Total value |
20 u |
50 u + 650 |
70 u + 650 |
$1 = 100¢
$17 = 17 x 100 = 1700¢
Ian has 13 more 50-cent coins than 20-cent coins.
Number of 20-cent coins = 1 u
Number of 50-cent coins = 1 u + 13
Total value of 20-cent coins
= 20 x 1 u
= 20 u
Total value of 50-cent coins
= 50 x (1 u + 13)
= 50 u + 650
Total value of the coins
= 20 u + 50 u + 650
= 70 u + 650
70 u + 650 = 1700
70 u = 1700 - 650
70 u = 1050
1 u = 1050 ÷ 70 = 15
Total number of coins
= 1 u + (1 u + 13)
= 2 u + 13
= 2 x 15 + 13
= 30 + 13
= 43
Answer(s): 43
