Question

Cost of 9pencils is equal to the cost of 4 pens.Cost of 13pencils and6pens is rs159. Whst is the cost of 21 pencils and17 pens together

Answer 1

Answer:

88.875 Rs

Step-by-step explanation:

let the cost of each pencil is x and pen is y

Cost of 9pencils is equal to the cost of 4 pens

9x=4y

9x-4y=0

Cost of 13pencils and6pens is rs159

13x+6y=159

by multiplying first equation with 6 and second equation with 4

54x-24y=0

52x+24y=159

by adding these two equations we get

106x=159

x=1.5

by substituting this value in first equation

9*1.5-4y=0

13.5=4y

y=3.375

the cost of 21 pencils and17 pens together

21x+17y=21*1.5+17*3.375=31.5+57.375=88.875