PSLE Liam saved a total of $31 in coins in his coin box.
16 of all the coins saved were one-dollar coins. There were 2 times as many one-dollar coins as twenty-cent coins. The remaining coins were ten-cent coins. How many coins did Liam save in his coin box altogether?
|
One-dollar |
Twenty-cent |
Ten-cent |
Total |
Comparison between the number of 3 types of coins |
1x2 2 u |
5x2 10 u |
6x2 12 u
|
Comparison between the number of one-dollar and twenty-cent coins |
2x1 |
1x1 |
|
|
Number |
2 u |
1 u |
9 u |
12 u |
Value |
1 |
0.2 |
0.1 |
|
Number x value |
2 u |
0.2 u |
0.9 u |
3.1 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 1 and 2 = 2
Total value of coins = 3.1 u
3.1 u = 31
1 u = 31 ÷ 3.1 = 10
Total number of coins
= 2 u + 1 u + 9 u
= 12 u
= 12 x 10
= 120
Answer(s): 120