Question 522140
plane speed	=x	mph									
wind speed	10	mph									
											
time with wind	2	hours									
time against wind(30mph)	4	hours									
Distance = same											
2(x+10)=4(x-30)
2x+20	=	4	x	-120					
4x-2x=20-120					
x 	=	140	mph	plane speed