Daniel has 20-cent coins and 50-cent coins. The total value of all his coins is $38. 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¢
$38 = 38 x 100 = 3800¢
Daniel 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 = 3800
70 u = 3800 - 650
70 u = 3150
1 u = 3150 ÷ 70 = 45
Total number of coins
= 1 u + (1 u + 13)
= 2 u + 13
= 2 x 45 + 13
= 90 + 13
= 103
Answer(s): 103