Maths (急) thx

1)
The selling price of the toy soldier,
= 50 * (1 + 50%)
= 50 * 150%
= 50 * 150/100
= 150/2
= 75
.'. The selling price of the toy soldier is $75

2)
The selling price of the watch,
= 400 * ( 1- 25%)
= 400 * 75%
= 400 * 75/100
= 300
.'. The selling price of the watch is $300

3)
Let $X be the cost price of the chair
X * (1 - 20)% = 88
X * 80% = 88
X * 80/100 = 88
X * 4/5 = 88
X *4 = 88*5
X *4 = 440
X = 110
.'. The cost price of the chair is $110

The loss of the chair,
= 110 - 88
= $22

4a)
Let $X be the cost price of the computer,
X * ( 1 +25)% = 7500
X * 125% = 7500
X * 125/100 = 7500
X * 125 = 7500*100
X * 125 = 750000
X = 750000/125
X = 6000
.'. The cost price of the computer is $6000

4b)
Sam's profit on the computer,
= 7500 - 6000
= $1500

2007-11-21 21:53:49 補充：
E 就話幫到你姐, test , exam 果d 就要靠自己ga la, 要努力 學好佢, 而唔係 努力抄好佢, =]

首先,你唔好將yahoo知識當係抄功課既地方.
因住比先生掘到你抄.
selling price=cost+profit=cost-loss
1.ans=ansX50%+cost
ans=costX2=$100
2.ans=cost-ansX25%
5/4 Xans=cost
ans=cost X4/5=$320
3.selling price=cost-loss
loss=88*20%=$17.6
cost=loss+selling price=$17.6+$88=$105.6
4.b.profit=7500*25%=$1875
a.cost=selling price-profit=7500-1875=$5625

1. $50 * (1+50%) = $75
2. $400 * (1-25%) = $300
3. C (1-20%) = $88
C = $110

4.a)
C (1 + 25%) = 7500
C = 6000
b) 7500 - 6000 = 1500