PSLE Archie saved a total of $55 in coins in his coin box.
110 of all the coins saved were one-dollar coins. There were 2 times as many one-dollar coins as ten-cent coins. The remaining coins were twenty-cent coins. How many coins did Archie save in his coin box altogether?
|
One-dollar |
Ten-cent |
Twenty-cent |
Total |
Comparison between the number of 3 types of coins |
1x2 2 u |
9x2 18 u |
10x2 20 u
|
Comparison between the number of one-dollar and ten-cent coins |
2x1 |
1x1 |
|
|
Number |
2 u |
1 u |
17 u |
20 u |
Value |
1 |
0.1 |
0.2 |
|
Number x value |
2 u |
0.1 u |
3.4 u |
5.5 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 = 5.5 u
5.5 u = 55
1 u = 55 ÷ 5.5 = 10
Total number of coins
= 2 u + 1 u + 17 u
= 20 u
= 20 x 10
= 200
Answer(s): 200