Question 311137
Gravies average driving speed is 4 kilometers per hour faster than Richards.
 In the same length of time it takes Gracie to drive 265 kilometers Richard drives 252 kilometers.
 What is gravies average speed?
:
Let s = g's speed
then
(s-4) = r's speed
:
Write a time equation; time = dist/speed
{{{265/s}}} = {{{252/((s-4))}}}
cross multiply
265(s-4) = 252s
265s - 1060 = 252s
265s - 252s = 1060
13s = 1060
s = {{{1060/13}}}
s = 81.538 km/hr is g's speed
:
;
Check the times, they should be equal: (77.538) = r's speed
265/81.538 = 3.25 hrs
252/77.538 = 3.25 hrs