勁急呀 F1數學問題(英文) 20點

Question 1
Percentage increase = increase/original x 100
=(15000-12000)/12000 x100
=25%

Question 2
Percentage decrease = decrease/original x 100
=(8400-7350)/8400 x 100
=12.5%

Question 3
Percentage decrease = decrease/original x 100
=37500/(212500+37500) x 100
=15%

Question 4
Percentage increase = increase/original x 100
=99/(599-99) x 100
=19.8%

Question 5
$100000 Loss of 22.5% = 100000 x (100-22.5)
=100000 x 77.5%
=100000 x 0.775
=$77500

Question 6
Profit of 40% = 100% + 40% = 140%
140% of 36 = 1.4 x 36
=$50.4 for a dozen pencils

dozen = 12
=50.4/12
=$4.2 for each pencil

Question 7
10 dozen = 10 x 12 = 120
120 eggs = $60

FIRST HALF OF THE EGGS:
60 eggs (half the eggs) = $30
50% profit of $30 = $15

SECOND HALF OF THE EGGS:
60 eggs = $30
30% profit of $30= $9

TOTAL PROFIT = 15 + 9
=$24 profit

Question 8
(let 'x' be the original price of the shoes)
$350 = 35% of x
**of = multiply, so:
350/0.35 = x
x= $1000

Question 9
let x = original cost of car
120000= 100% + 25% = 125%
120000= 125% of x
x= 120000/1.25
=$96000

Question 10
let x be original cost of car
225=75% of x
x= 225/ 0.75
=$300