Math word problem help???

Andy’s average driving speed for a 4-hour trip was 45 miles per hour. During the first 3 hours he drove 40 miles per hour. What was his average speed for the last hour of his trip?

Andy’s total distance:4*45=180 miles
Andy’s 3 hours distance:40*3=120 miles
The last one hour distance：180-120=60 miles
his the last hour average speed:60miles/1hour=60km/h

Her average speed for the last hour was 60 miles per hour. This is because the average is taken by the speed multiplied by the hour. For 3 hours the average speed was 40 and te total miles was 120. And the 3 hours had an average of 45 miles per hour and a total of 180 miles. You subtract 120 from 180 to find the last hour of driving was 60 miles per hour.

d=rt

d = 45 x 4 = 180

d2 = 40 x 3 = 120

d3 = d - d2 = 180 - 120 = 60

r = d / t = 60 / 1 = 60 mph.

60.

4*45=180. ..... 3*40=120 ... So answer is 60 mph last hour