Sam has 10-cent coins and 20-cent coins. The total value of all his coins is $37. He has 5 less 10-cent coins than 20-cent coins. How many coins does he have altogether?
| |
10-cent |
20-cent |
Total |
| Number |
1 u |
1 u + 5 |
2 u + 5 |
| Value |
10 |
20 |
|
| Total value |
10 u |
20 u + 100 |
30 u + 100 |
$1 = 100¢
$37 = 37 x 100 = 3700¢
Sam has 5 more 20-cent coins than 10-cent coins.
Number of 10-cent coins = 1 u
Number of 20-cent coins = 1 u + 5
Total value of 10-cent coins
= 10 x 1 u
= 10 u
Total value of 20-cent coins
= 20 x (1 u + 5)
= 20 u + 100
Total value of the coins
= 10 u + 20 u + 100
= 30 u + 100
30 u + 100 = 3700
30 u = 3700 - 100
30 u = 3600
1 u = 3600 ÷ 30 = 120
Total number of coins
= 1 u + (1 u + 5)
= 2 u + 5
= 2 x 120 + 5
= 240 + 5
= 245
Answer(s): 245
