PSLE Perry saved a total of $13 in 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. How many coins did Perry save in his coin box altogether?
|
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 value of coins = 6.5 u
6.5 u = 13
1 u = 13 ÷ 6.5 = 2
Total number of coins
= 3 u + 1 u + 17 u
= 21 u
= 21 x 2
= 42
Answer(s): 42