1.If 20 is increased by b,the result is 120 percent of b.Find the value of b.
2.The marked price of a television is set at a profit of 20 percent.Then it is sold at a discount of 20 percent and the loss is $64.Find the cost price of the television.
maths question
2007-02-05 5:24 am
回答 (2)
2007-02-05 5:35 am
✔ 最佳答案
1. 20+b=(120%)b20+b=1.2b
20=0.2b
b=100
2. Let $x be the cost price.
(120%)x(80%)=x-64
(1.2)x(0.8)=x-64
0.96x=x-64
0.04x=64
x=1600
^^"
2007-02-05 5:36 am
1. 20 + b = 1.2 * b
=> 20 = b (1.2 - 1) = 0.2b
=> b = 100
2. (eq a) m = 1.20 * x (profit is 120% of cost)
(eq b) (1.00 - 0.2) * m = x - 64 (television is sold at a 20% discount and the loss is $64)
substituting eq a into eq b, 0.8 * 1.20 * x = x - 64 = 0.96 x
=> 64 = (1 - 0.96) x
=> x = 64 / 0.4 = $160
2007-02-04 21:37:37 補充：
sorry it's supposed to be 64/0.04 = $1600
=> 20 = b (1.2 - 1) = 0.2b
=> b = 100
2. (eq a) m = 1.20 * x (profit is 120% of cost)
(eq b) (1.00 - 0.2) * m = x - 64 (television is sold at a 20% discount and the loss is $64)
substituting eq a into eq b, 0.8 * 1.20 * x = x - 64 = 0.96 x
=> 64 = (1 - 0.96) x
=> x = 64 / 0.4 = $160
2007-02-04 21:37:37 補充：
sorry it's supposed to be 64/0.04 = $1600
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