Taking into account reaction time the distance d in feet tha

Taking into account reaction time, the distance d in feet that a car requires to come to a complete stop while traveling r miles per hour is given by the following function. d(r) = 6.88r - 88.50 Find the inverse of d(r), written r(d). Then predict the speed that a car was traveling if the distance required to stop was 350 feet. Round to the nearest whole number and give units.

Solution

For part \"a\", write the equation like this to make it a little less confusing by eliminating d(r) and just make it \"d\" for distance:
d = 6.88r – 88.50

Then isolate the \"r\" term by dividing both sides by 6.88:
d / 6.88 = r -12.86

Then add 12.86 to both sides:
(d / 6.88) + 12.86 = r

Then re-arrange it and make distance the independent variable:
r(d) = (d / 6.88) + 12.86

For part \"b\", do this:
r(350) = (350 / 6.88) + 12.86
r(350) = 63.73 mph