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primary 5 | Maths
| Percentage

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Plz help solve this question with working. Thx in advance

40% = 4/10

1 - 4/10 = 6/10

Let Mina have 4 units at the end, Linda have 6 units, a total of 10 units.

Mina gave 3/7 of her stickers back to Linda in return.

1 - 3/7 = 4/7

So she had 4/7 of it left in the end, and that equals 4 units.

Looking at the numerator, notice that it is also 4.

Since 4/7 can be thought of as 4 units out of 7, Mina had 7 units before giving to Linda.

So she gave 3 units to Linda.

Stickers Linda had before given back by Mina = 6units - 3 units

= 3 units

Now before Mina gave back to Linda, Linda had given ⅓ of her stickers to Mina.

1 - ⅓ = ⅔

She had ⅔ of it left and that equals the 3 units.

So ⅓ = 3 units ÷ 2 = 1½ units.

So Linda gave 1½ units to Mina.

Linda's stickers at first

= 3 units + 1½ units

= 4½ units

Mina's stickers at first

= 7 units - 1½ units

= 5½ units

Difference at first

= 5½ units - 4½ units

= 1 unit

1 unit = 80 stickers

Mina gave 3 units to Linda.

3 units

= 80 stickers x 3

= 240 stickers

Since Linda gave ⅓ of her stickers to Mina at the start and Mina gave 3/7 back, to make things easier,

we make the denominator common.

3 x 7 = 21

Let Linda's stickers at first be 21 units.

Then Mina's stickers = 21 units + 80

Total = 42 units + 80

Linda gave ⅓ of her stickers, which

= ⅓ x 21 units (or 21 units ÷ 3)

= 7 units

Linda stickers after giving Mina

= 21 units - 7 unit s

= 14 units

Mina's stickers after receiving from Linda

= 21 units + 80 + 7 units

= 28 units + 80

Now, Mina gave 3/7 of her stickers back to Linda.

3/7 of it = 3/7 x (28 units + 80)

= 12 units + 34 2/7

(Don't worry about the fractions , it will be resolved later)

Linda's stickers in the end

= 14 units + 12 units + 34 2/7

= 26 units + 34 2/7

Mina's stickers in the end

= 28 units + 80 - 12 units - 34 2/7

= 16 units + 45 5/7

Difference

= 26 units + 34 2/7 - 16 units - 45 5/7

= 10 units - 11 3/7

Difference also = 60% - 40% = 20%

So 20% → 10 units - 11 3/7

Total = 100% → 5 x (10 units - 11 3/7)

= 50 units - 57 1/7

Now we know total also = 42 units + 80 ①

So 42 units + 80 = 50 units - 57 1/7

50 units - 57 1/7 = 42 units + 8 units - 57 1/7

Comparing this and the first equation,

We see that 8 units - 57 1/7 = 80

8 units = 80 + 57 1/7 = 137 1/7

1 unit = 137 1/7 ÷ 8 = 17 1/7

Mina gave 12 units + 34 2/7

= 12 x (17 1/7) + 34 2/7

= 205 5/7 + 34 2/7

= 240 stickers