Question

the cost of a pencil is 25 cents more than the cost of an eraser. if the cost of 8 pencils and 10 eraser is $12.80, find the cost of each

Answer 1

let the cost of each erasers be 'x ' and the cost of each pencils be 'y' .

First case:
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cost of each pencils = 25 % more than the cost of eraser

cost of each pencils y = x + 25% of x

y = x + 0.25x = 1.25x

cost of each pencils y = $1.25x. -----(1)

second case:
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cost of 8 pencils and 10 erasers

= $12.80

8y + 10x = 12.80

8y + 10x = 12.80

8 ( 1.25x ) + 10x = 12.80

10x + 10x = 12.80

20x = 12.80 => x =$0.64

put value of 'x' in (1) , we get

y = 1.25x = 1.25 × 0.64

y = $0.80

Answer:
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cost of each pencils y = $0.80

cost of each erasers x = $0.64

Answer 2

Pencil Eraser

25+x x

8(25+x)+10x=1280 [ 1 doller=100 cent

12.80 doller=1280 cent

200+8x+10x=1280

200+18x=1280

18x=1280-200

18x=1080

X=1080/18

X=60

Cost of a eraser= x = 60

Cost of a pencil= 25+x=85