so hmm notice the picture below
one is 7x5x1.75 the volume of a rectangular prism is V = length * width * height
so 7*5*1.75 gives us 61.25 ft³
the second one, is larger by some width and length we dunno, but we know that it required that 61.25 plus an extra 17.5 to fill it up, so its volume is 61.25 + 17.5 or 78.75
the height is the same... so [tex]\bf V=l\cdot w\cdot h\qquad
\begin{cases}
l=length\\
w=width\\
h=height\\ --------\\
h=1.75\\
V=78.75
\end{cases}\implies 78.75=lw\cdot 1.75
\\\\\\
\cfrac{78.75}{1.75}=lw\implies 45=lw[/tex]
so.. if you factor 45, to two factors, one will be the length, the other the width
