Answer:
2.25 square inches
Step-by-step explanation:
we know that
The scale is [tex]1\ inch: 20\ miles[/tex]
That means
1 inch on a map represent 20 miles in the city
so
An area of [tex](1)(1)=1\ in^2[/tex] on a map represent an area of [tex](20)(20)=400\ mi^2[/tex] in the city
Applying proportion
[tex]\frac{1}{400}\ \frac{in^2}{mi^2}=\frac{x}{900}\ \frac{in^2}{mi^2}\\\\x=900/400\\\\x=2.25\ in^2[/tex]