Question

A plane flies round-trip to Philadelphia. If flies to Philadelphia at 220 miles per hour and back home with a tailwind at 280 miles per hour. If the total trip takes 6.5 hours, how many miles does the plane fly round-trip?

Answer 1

$v=\frac{s}{t},\ where\ V-speed,\ s-distance,\ t-time\\v*t=s\\\\ \left \{ {{v_1*t_1=s} \atop {v_2*t_2=s}} \right.\\\\t_1=6,5-t_2\\\\ \left \{ {{220(6,5-t_2)=s} \atop {280*t_2=s}} \right. \\\\ 220(6,5-t_2)=280*t_2\\ 1430-220t_2=280t_2\ \ \ |Add\ 220t_2\\ 1430=500t_2\ \ \ |Divide\ by\ 500\\t_2=2,86h\\\\ s=t_2*v_1\\ s=2,86*280=800,8\\ 2s=1601,6miles\\\\ Plane\ flew\ 1601,6\ miles\ in\ round\ trip.$