What is the answer for B in this?

Acar started driving from city a to city b, distance between which is 620 miles, at a rate of 60 mph. two hours later a truck left city b and started moving towards city a at a rate of 40 mph. what distance from city a is the point where the truck and the car will meet?

Find the maximum value of p= 4x + 5y subject to the following constraints :

The product of sin 30 degrees and sin 60 degrees is same as the product of