Question 959269
R=rate of plane; W=rate of wind
R+W=2200km/4hrs=550km/hr
R-W=1820km/4hrs=455 km/hr
R-W=455km/hr Add W to each side.
R=455km/hr+W
R+W=550km/hr Substitute for R.
455km/hr+W+W=550km/hr Subtract 455km/hr from each side.
2W=95km/hr Divide each side by 2.
W=47.5 km/hr ANSWER B): Speed of the wind was 47.5 km/hr.
R=455km/hr+W=455km/hr+47.5km/hr=502.5km/hr
ANSWER A): The rate of the plane in calm air was 502.5 km/hr.
CHECK:
2200km/(502.5km/hr+47.5km/hr)=1820km/(502.5km/hr-47.5km/hr)
2200km/(550km/hr)=1820km/(455km/hr)
4hrs=4hrs