Question

10. The cost of four pens,
five erasers and
six sharpeners is 47. The cost of six pens,
seven erasers and nine sharpeners is 69. Find the
cost of an eraser (in). Rupees​

Answer 1

Step-by-step explanation:

Suppose one eraser, one sharpener and one pencil cost e,s and p rupees respectively.

Given:

5e+7s+9p=100 ........... (1) and 2e+6s+10p=80 ........... (2)

So, from (2)

e+3s+5p=40 ⟹ e=40−3s−5p

Substituting in (1) we get,

5(40−3s−5p)+7s+5p=40 by solving we get s=10−2p ......... (3)

Substitute in (2) we get,

e−p=10 ........... (4)

Adding (3) and (4) we get,

e+s+p=20.

Hence, option C is correct.