Posted by **Al** on Thursday, April 19, 2012 at 12:03am.

Sasa had some 20-cent and 50-cent coins.

7/8 of the coins were 20-cent coins and the rest were 50-cent coins.After Sasa had spent $72.50 worth of 50-cent coins and 5/7 of the 20-cent coins, she had 2/7 of the coins left. Find the total amount of money Sasa left.

- math -
**Steve**, Thursday, April 19, 2012 at 12:12pm
let there be:

c coins

t 20¢ coins

f 50¢ coins

7/8 c = t

1/8 c = f

so, t = 7f

72.50 is 145 of the 50¢ coins

(f + t) - 145 - (5/7 t) = 2/7 (f+t)

since t = 7f,

f + 7f - 145 - 5f = 2/7 * 8f

f = 203

so, t = 1421

and 1624 coins in all

check:

1624 - 145 - 5/7 (1421)

= 1624 - 145 - 1015

= 464

464 is 2/7 of 1624

- math -
**Al**, Thursday, April 19, 2012 at 10:03pm
Thank you, Steve.

- math -
**Rochelle**, Friday, November 25, 2016 at 5:22pm
The first answer is wrong. What is being asked is the amount. 464 is too much compared to $72.50 which is the combination of 50c and 5/7 of 20c.

Listing method is used to find the answer.

The total fraction for the 20c and 50c is 8/8.

7/8 were 20c

1/8 were 50c

Singaporean Math is applied using the block method.

7 units = 20c

1 unit = 50c

8 units in all

If the denominator is 8, find a multiple that will match the given amount of $72.50. The multiple is equivalent to 1 unit.

The multiple is 48.

Each unit is 48.

$72.50 is 5units of 20c and 1unit of 5c.

48 x 5 x .20 = $48

48 x .50 = $24

$48 + $24 = $72

Add .50 to make it $72.50

The question is the total amount of money left which 2/7.

So that is 48 x 2 x .20 = $19.20

48 48 48 48 48 48 48 49

20c 20c 20c 20c 20c 20c 20c 50c

There is a total of 336pcs 20c coins amounting to $67.20 and

49pcs 50c coins amounting to $24.50

=$91.70 - $19.20 = $72.50

All 50c were spent. Only 2/7 of 20c were left.

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