Question

Two planes fly toward each other. They are 3500 kilometers apart. They pass
each other after 7.5 hours. If their speeds differ by 65 kilometers per hour, what are their speeds?​

Answer 1

Given:

Two planes fly toward each other. They are 3500 kilometers apart.

They pass  each other after 7.5 hours.

Their speeds differ by 65 kilometers per hour.

To find:

Their speed.

Solution:

Let speed of one plane be x km/h.

So, speed of second plane is x+65 km/h.

Relative speed = x+(x+65) km/h

We know that,

$Speed=\dfrac{Distance}{Time}$

$x+(x+65)=\dfrac{3500}{7.5}$

$2x+65=\dfrac{3500}{7.5}$

Multiply both sides by 7.5.

$15x+487.5=3500$

$15x=3500-487.5$

$15x=3012.5$

Divide both sides by 15.

$x=\dfrac{3012.5}{15}$

$x\approx 200.83$

Speed of first plane = 200.83 km/h.

Speed of second place = 200.83+65 = 265.83 km/h

Therefore, their speeds are 200.83 km/h and respectively.