Question

Avantika completed her journey of 136 km in 6 h. A part of this journey was travelled at 15 km/h and the remaining part at 18 km/h. What part of the journey was travelled at 18 km/h?

Answer 1

Let the distance travelled at the first part be x km and second part be y km.
CASE 1
total distance = 136 km
x+y=136 --------------------  (1)
CASE 2

FOR 1ST PART
distance = x km
speed = 15 km/hr
time = $\frac{x}{15}$hr

FOR 2ND PART
distance = y km
speed = 18 km/hr
time = $\frac{y}{18}$hr

⇒$\frac{x}{18} + \frac{y}{15}=6 \\ 15x+18y=1620$
3(6x+5y)=1620
6x+5y= 540 -------------------------- (2)

now solve (1) and (2)