Question 977295
r, normal speed



__________________speed___________time___________distance
Normal_____________r_______________{{{1/2}}}___________d
Slower____________r-10____________{{{1/2+1/6}}}_________d


Revise the data


__________________speed___________time___________distance
Normal_____________r_______________{{{1/2}}}___________d
Slower____________r-10____________{{{2/3}}}_____________d


{{{system(r*(1/2)=d,(r-10)(2/3)=d)}}}


{{{r=2d}}}
-
{{{(2d-10)(2/3)=d}}}
{{{2(2d-10)=3d}}}
{{{4d-20=3d}}}
{{{highlight(d=20)}}}