Question 442300
x, speed of boat in still water
y, speed of river current


{{{(x+y)(10)=210}}} and {{{(x-y)(70)=210}}}


{{{x+y=21}}} and {{{x-y=3}}}


{{{2x=24}}}
{{{x=12}}} boat in still water


{{{2y=18}}}
{{{y=9}}} river current speed