Question 1151347
 
The ratio of the two speeds is {{{100:80 = 5:4}}}.
Since the distances are the same, the ratio of times spent at the two speeds is {{{4:5}}}.


{{{(4*100(km/h) + 5*80(km/h))/(4+5)=(400(km/h) + 400(km/h))/9=800(km/h)/9=88.89(km/h)}}}