Answer:
the speed of the plane when there is no wind is 212.25 mi/hr
Step-by-step explanation:
Let v represent the speed of the plane without wind.
Wind speed = 20.1 mi/hr
The resultant speed with wind is;
v + 20.1 mi/hr
The resultant speed against wind is;
v - 20.1 mi/hr
Let t represent the time for the travel.
With wind;
(v+20.1)t = 630 ......1
Against wind;
(v-20.1)t = 521 ......2
Divide equation 1 by 2
(v+20.1)/(v-20.1) = 630/521
Cross multiply;
521(v+20.1) = 630(v-20.1)
Collecting like terms;
v(630-521) = 20.1(630+521)
v = 20.1(1151)/109
v = 212.25 mi/hr
the speed of the plane when there is no wind is 212.25 mi/hr