PSLE Howard had a total of 210 coins in his coin box.
17 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 |
6x3 18 u |
7x3 21 u
|
Comparison between the number of one-dollar and ten-cent coins |
3x1 |
1x1 |
|
|
Number |
3 u |
1 u |
17 u |
21 u |
Value |
1 |
0.1 |
0.2 |
|
Number x value |
3 u |
0.1 u |
3.4 u |
6.5 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 = 21 u
21 u = 210
1 u = 210 ÷ 21 = 10
Total value of coins
= 3 u 0.1 u 3.4 u
= 6.5 u
= 6.5 x 10
= $65
Answer(s): $65