PSLE Ivan saved a total of $30 in coins in his coin box.
13 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 Ivan 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 |
2x2 4 u |
3x2 6 u
|
Comparison between the number of one-dollar and twenty-cent coins |
2x1 |
1x1 |
|
|
Number |
2 u |
1 u |
3 u |
6 u |
Value |
1 |
0.2 |
0.1 |
|
Number x value |
2 u |
0.2 u |
0.3 u |
2.5 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 = 2.5 u
2.5 u = 30
1 u = 30 ÷ 2.5 = 12
Total number of coins
= 2 u + 1 u + 3 u
= 6 u
= 6 x 12
= 72
Answer(s): 72