Question

the price of 4 books and 10 pens is rs100 and price of 7 books and 9 pens costs rs158 then find the cost of 2 books and 5 pens​

Answer 1

ANSWER

50

method

x=book

Y=pen

4x+10y=100

7x+9y=158

Multiplying 4x+10y=100 by 9

And multiplying 7x+9y=158 by 10

36x+90y=900(equation 1)

70x+90y=1580(equation 2)

Equation 1- equation 2

Gives

-34x=-680

X=-680/-34

X=20

therefore

20*4+10y=100

80+10y=100

10y=100-80

10y=20

Y=10

Cost of 2 books

20*2=40

Cost of 5 pen

5*2=10

Total 40+10

50