Question

$3$ pens, $4$ note books together cost Rs. $110$, and $7$ pens $5$ note books cost Rs. $170$. Find the cost of each pen and note book.

Answer 1

Solution:

$3$ Pen $+4$ Notebook $=110$ rupees

Multiply by $5$,

$15$ Pen $+20$ Notebook $=550$ rupees

$7$ Pen $+5$ Notebooks $=170$ rupees

Multiply by $4$,

$28$ Pen $+20$ Notebook $=680$ rupees

$15$ Pen $+20$ Notebook $=550$ rupees

Equating and solving for Pen,

Cancelling notebook,

$13$ Pen $=130$ Hence,

Pen $=10$ rupees

Substituting,

$3\left(10\right)+4$ Notebook $=110$

$4$ Notebook $=110-30$ Hence,

Notebook $=20$ rupees