Question

5books and 7pens together cost$79,whereas 7books and 5pens together cost$77. Find the total cost of 1books and 2pebs

Answer 1

Answer:

Step-by-step explanation:

Let the pens be y and books be x

A/Q,

5x+7y=79 ------(1)

And 7x+5y=77-------(2)

(2)-(1),

7x+5y-5x-7y= 77-79

=> 2x-2y= -2

=> y-x= 2

=> y= x+2-----(3)

(1) implies,

5x+7y=79

=>5x+7(x+2)=79

=>5x+7x+14=79

=> 12x= 65

=> x= 5.4 (approx)

(3) implies,

y=x+2=5.4+2=7.4

Therefore cost of 1 book and 2 pens,

x+2y= 5.4+14.8= Rs. 20.2