a rectangular photo is 20 inches wide and 25 inches tall. Anlargement of that photo is 40 inches tall

We want to find the width of the enlargement, where its length is 40 inches, and the original size is 20 inches wide and 25 inches tall.
We can state a proportion, calling by x the width of the enlargement, and we get:
[tex]\frac{20}{25}=\frac{x}{40}[/tex]We multiply means and extremes:
[tex]\begin{gathered} 20\cdot40=25\cdot x \\ 800=25\cdot x \\ \text{And we solve for x:} \\ x=\frac{800}{25}=32 \end{gathered}[/tex]This means that the width of the enlargement 32 inches.