PSLE Billy saved a total of $108 in coins in his coin box.
29 of all the coins saved were one-dollar coins. There were 3 times as many one-dollar coins as fifty-cent coins. The remaining coins were twenty-cent coins. How many coins did Billy save in his coin box altogether?
|
One-dollar |
Fifty-cent |
Twenty-cent |
Total |
Comparison between the number of 3 types of coins |
2x3 6 u |
7x3 21 u |
9x3 27 u
|
Comparison between the number of one-dollar and fifty-cent coins |
3x2 |
1x2 |
|
|
Number |
6 u |
2 u |
19 u |
27 u |
Value |
1 |
0.5 |
0.2 |
|
Number x value |
6 u |
1 u |
3.8 u |
10.8 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 2 and 3 = 6
Total value of coins = 10.8 u
10.8 u = 108
1 u = 108 ÷ 10.8 = 10
Total number of coins
= 6 u + 2 u + 19 u
= 27 u
= 27 x 10
= 270
Answer(s): 270