Question 751278
The volume given for jar A is in units of cubic inches.  Already a volume unit, so no need to be confused about different kinds of units or dimensions. 


{{{400/2800=5/c}}}  where c is the volume in cubic inches for jar B.


The reciprocals are also equal:
{{{2800/400=c/5}}}
{{{7=c/5}}}
{{{7*5=(c/5)*5}}}
{{{c=35}}} {{{inch^3}}}