Daniel has 5-cent coins and 10-cent coins. The total value of all his coins is $11. He has 11 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 + 11 |
2 u + 11 |
Value |
5 |
10 |
|
Total value |
5 u |
10 u + 110 |
15 u + 110 |
$1 = 100¢
$11 = 11 x 100 = 1100¢
Daniel has 11 more 10-cent coins than 5-cent coins.
Number of 5-cent coins = 1 u
Number of 10-cent coins = 1 u + 11
Total value of 5-cent coins
= 5 x 1 u
= 5 u
Total value of 10-cent coins
= 10 x (1 u + 11)
= 10 u + 110
Total value of the coins
= 5 u + 10 u + 110
= 15 u + 110
15 u + 110 = 1100
15 u = 1100 - 110
15 u = 990
1 u = 990 ÷ 15 = 66
Total number of coins
= 1 u + (1 u + 11)
= 2 u + 11
= 2 x 66 + 11
= 132 + 11
= 143
Answer(s): 143