Question

A train left town a for town b at a speed of 36km/,h. Another train left town b for town a at a speed of 64km/hr. If the two towns were 900km apart, when did the two trains meet

Answer 1

Suppose they meet $x$  hours after start.

Distance covered by $a$ in $x$  hours $= 36x \ km.$

Distance covered by $b$ in $x$  hours $= 64x \ km.$

They will meet when

$$36x+64x=900$$

$$100x=900$$

$$x=\dfrac{900}{100}$$

$$x=9$$

The trains will meet  $9$  hours after start.