PSLE Jenson saved a total of $299 in coins in his coin box.
710 of all the coins saved were one-dollar coins. There were 4 times as many one-dollar coins as twenty-cent coins. The remaining coins were ten-cent coins. How many coins did Jenson save in his coin box altogether?
|
One-dollar |
Twenty-cent |
Ten-cent |
Total |
Comparison between the number of 3 types of coins |
7x4 28 u |
3x4 12 u |
10x4 40 u
|
Comparison between the number of one-dollar and twenty-cent coins |
4x7 |
1x7 |
|
|
Number |
28 u |
7 u |
5 u |
40 u |
Value |
1 |
0.2 |
0.1 |
|
Number x value |
28 u |
1.4 u |
0.5 u |
29.9 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 7 and 4 = 28
Total value of coins = 29.9 u
29.9 u = 299
1 u = 299 ÷ 29.9 = 10
Total number of coins
= 28 u + 7 u + 5 u
= 40 u
= 40 x 10
= 400
Answer(s): 400