F.1 Maths

1.Mary sells an electric kettle at $600 and the profit per cent is 20%.

(a)Find the cost price of the electric kettle.
Let the cost price of the electric kettle be $x
x(1+20%)=600
1.2x=600
x=500
Therefore,the cost price of the electric kettle is $500

(b)If she decreases the selling price by55%, find her loss per cent.
the selling price=(600)(1-55%)=600(45%)=600(0.45)=$270
her loss per cent
=[(500-270)/500]*100%
=46%

2.The marked price of a television is set at a profit of 20%. Then it is sold at a discount of 20% and the loss is $64. Find the cost price of the television.
Let the cost price of the television be $x
x-(1+20%)x(1-20%)=64
x-(1.2)(0.8)x=64
(1-0.96)x=64
x=64/0.04
x=1600
Therefore,the cost price of the television is $1600

1.
(a)let x be the cost price
(1+20%)x=600
120%x=600
x=600/120%
x=500
(b) 600*(1-55%)
=600*45%
=270
=the marked price
270/500*100%
=54%
2.let x be the cost price of the television
x-(x+x20%-(x20%)20%)=64
x-x-x20%+(x20%)20%=64
-x20%+(x20%)20%=64
20%=64
because 20%=64
100%=320
so the cost price of the television.

1a) 600/ (1+20%)
= $500

b) selling price = 600 x (1 - 55%) = $270
Percentage loss = (500 - 270)/ 500 = 46%

2. let the cost of TV be c
c (1+20%) (1-20%) = c - 64
c = $1600