PSLE John saved a total of $42 in coins in his coin box.
12 of all the coins saved were one-dollar coins. There were 3 times as many one-dollar coins as twenty-cent coins. The remaining coins were fifty-cent coins. How many coins did John save in his coin box altogether?
|
One-dollar |
Twenty-cent |
Fifty-cent |
Total |
Comparison between the number of 3 types of coins |
1x3 3 u |
1x3 3 u |
2x3 6 u
|
Comparison between the number of one-dollar and twenty-cent coins |
3x1 |
1x1 |
|
|
Number |
3 u |
1 u |
2 u |
6 u |
Value |
1 |
0.2 |
0.5 |
|
Number x value |
3 u |
0.2 u |
1 u |
4.2 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 1 and 3 = 3
Total value of coins = 4.2 u
4.2 u = 42
1 u = 42 ÷ 4.2 = 10
Total number of coins
= 3 u + 1 u + 2 u
= 6 u
= 6 x 10
= 60
Answer(s): 60