PSLE Will had a total of 36 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 ten-cent coins. The remaining coins were twenty-cent coins. What was the total value of all the coins in his coin box?
|
One-dollar |
Ten-cent |
Twenty-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 ten-cent coins |
3x1 |
1x1 |
|
|
Number |
3 u |
1 u |
2 u |
6 u |
Value |
1 |
0.1 |
0.2 |
|
Number x value |
3 u |
0.1 u |
0.4 u |
3.5 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 1 and 3 = 3
Total number of coins = 6 u
6 u = 36
1 u = 36 ÷ 6 = 6
Total value of coins
= 3 u 0.1 u 0.4 u
= 3.5 u
= 3.5 x 6
= $21
Answer(s): $21