Question 1207792
#2, very very routine exercise


Water with nothing dissolved in it for practical purposes,  0% salt.


If adding v ounces,  (but you likely should mean, "fluid ounces") then

{{{(0.10*64+0*v)/(64+v)=0.02}}}



#1

Larger Pump, {{{1/(c-4)}}}, its pump-out rate, unit of TANK per HOUR

Smaller Pump rate, {{{1/c}}}

BOTH pumps together, rate,  {{{1/(c-4)+1/c}}}


Description give that the two pump working together do the job in 5 hours.
{{{highlight_green(1/(c-4)+1/c=1/5)}}}