Question

Cost of nine pencils is equal to the cost of four pens. cost of thirteen pencils and six pens is rs. 159. what is the cost of twenty one pencils and seventeen pens together?

Answer 1

21 pencils = rs126 and 17pens=229.5. total = 355.5

Answer 2

Hey.

Here is the answer.

let cost of one pencil = x

cost of 9 pencil = 9x

so, cost of 4 pen = 9x

so, cost of 1 pen = 9x/4

Also, cost of 13 pencil and 6 pen is 159

or, 13x + 6×(9x/4) =159

or, 26x + 27x = 159×2

or, 53x = 159×2

or, x = 159×2/53 =6

so, cost of one pencil is rs 6

cost of one pen is 9×6/4= rs 13.5

Hence cost of 21 pencil = 21×6= rs 126

cost of 17 pen = 17×13.5 = rs 229.5

So, together, total cost = rs 355.5

Thanks.