Xavier has 20-cent coins and 50-cent coins. The total value of all his coins is $13. He has 12 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 + 12 |
2 u + 12 |
| Value |
20 |
50 |
|
| Total value |
20 u |
50 u + 600 |
70 u + 600 |
$1 = 100¢
$13 = 13 x 100 = 1300¢
Xavier has 12 more 50-cent coins than 20-cent coins.
Number of 20-cent coins = 1 u
Number of 50-cent coins = 1 u + 12
Total value of 20-cent coins
= 20 x 1 u
= 20 u
Total value of 50-cent coins
= 50 x (1 u + 12)
= 50 u + 600
Total value of the coins
= 20 u + 50 u + 600
= 70 u + 600
70 u + 600 = 1300
70 u = 1300 - 600
70 u = 700
1 u = 700 ÷ 70 = 10
Total number of coins
= 1 u + (1 u + 12)
= 2 u + 12
= 2 x 10 + 12
= 20 + 12
= 32
Answer(s): 32
