Ying Zyiyu covered the first 300 miles of a trip going at 60 mph and the last hundred going at 40 mph. What was his average speed for the entire trip?

53.33mph

Step-by-step explanation:

Let's calculated the total time spent on the journey first;

For the first 300miles the time spent is ;

From Distance = speed× time

time = Distance/ speed

= 300/60 = 5 hours

Similarly for the last 100mile the time taken is ;

100/40 = 2.5 hours

Total time spent = 5 +2.5 = 7.5 hours

Total distance covered 400miles

Therefore average speed = 400/7.5 =53.33mph

answer is the third choice:

3x^5+4x^4+x^3+2x^2-10x-7=0

step-by-step explanation:

b and c

step-by-step explanation: