Tom has 20-cent coins and 50-cent coins. The total value of all his coins is $16. He has 11 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 + 11 |
2 u + 11 |
| Value |
20 |
50 |
|
| Total value |
20 u |
50 u + 550 |
70 u + 550 |
$1 = 100¢
$16 = 16 x 100 = 1600¢
Tom has 11 more 50-cent coins than 20-cent coins.
Number of 20-cent coins = 1 u
Number of 50-cent coins = 1 u + 11
Total value of 20-cent coins
= 20 x 1 u
= 20 u
Total value of 50-cent coins
= 50 x (1 u + 11)
= 50 u + 550
Total value of the coins
= 20 u + 50 u + 550
= 70 u + 550
70 u + 550 = 1600
70 u = 1600 - 550
70 u = 1050
1 u = 1050 ÷ 70 = 15
Total number of coins
= 1 u + (1 u + 11)
= 2 u + 11
= 2 x 15 + 11
= 30 + 11
= 41
Answer(s): 41
