Question

7. Mohit's mother is 6 times as old as he is now. After 2 years Mohit's mother will be 5 times as old as.
Mohit will be then. What are their present ages?
8. A pen costs 8 times as that of a pencil. If Hari buys 5 pencils and 2 pens and pays 126, what is
DA​

Answer 1

S O L U T I O N 7:

Let the Mohit's age be r years. & the Mohit's mother be 6r years .

$\underbrace{\bf{2\:years\:later\::}}$

The age of Mohit will be = (r + 2) years .

The age of Mohit's mother will be = (6r + 2) years .

$\underline{\underline{\tt{According\:to\:the\:question\::}}}$

$\mapsto\tt{(6r+2) = 5(r+2)}$

$\mapsto\tt{6r+2 = 5r + 10}$

$\mapsto\tt{6r-5r = 10 - 2}$

$\mapsto\bf{r = 8\:years }$

Thus;

The present age of Mohit = r = 8 years .

The present age of Mohit's Mother = 6r = 6 × 8 = 48 years .

S O L U T I O N 8:

Let the cost price of a pencil be Rs.r & let the cost price of a pen be Rs.8 respectively .

$\underline{\underline{\tt{According\:to\:the\:question\::}}}$

$\mapsto\tt{5\:pencil's + 2\:pen's = 126}$

$\mapsto\tt{5\:(r) + 2\:(8r) = 126}$

$\mapsto\tt{5r + 16r = 126}$

$\mapsto\tt{21r= 126}$

$\mapsto\tt{r= \cancel{126/21}}$

$\mapsto\bf{r=Rs.6}$

Thus;

The cost price of a pencil = r = Rs.6 .

The cost price of a pen = 8r = Rs.8 × 6 = Rs.48 .