Question 960627
t, expected time
r, expected speed



________________________speed___________time_________distance
Expected________________r_______________t____________150
Actual__________________r-10____________t+1/2_________150


The question is to find r and t+30.
30 minutes is {{{1/2}}} hour.


RT=D Uniform Travel Rates Rule.
Setup two equations in r and t, and solve.
{{{system(rt=150,(r-10)(t+1/2)=150)}}}