Question

A man completed a trip of $136$ km in $8$ hours. Some parts of the trip was covered at $15$ km/hr and the remaining at $18$ km/hr. Find the part of the trip covered at $18$ km/hr.

• A. $120$ km
• B. $109$ km
• C. $57$ km
• D. $96$ km

Answer 1

The correct option is D $96$ km

Given :

Man completed a trip of $136$ km in $8$ hrs

Therefore he completes a trip of $17$ km per hour

Suppose he covered $x$ distance at $15$ km/hr

and $y$ distance at $18$ km/hr

$\therefore x+y=136$ ...(1)

and $\frac{x}{15}+\frac{y}{18}=8$ ...(2)

Multiplying (2) by $90$, we get

$6x+5y=720$ ...(3)

By solving equations (1) and (3), we get

$x=40$

$\therefore 40+y=136$

$\therefore y=96$ km