First let's use two rules of three to determine the actual dimensions of the building.
For the length, we have:
[tex]\begin{gathered} 1\text{ inch}\to15\text{ feet} \\ 4.2\text{ inches}\to x\text{ feet} \\ \\ \frac{1}{4.2}=\frac{15}{x} \\ x=15\cdot4.2=63 \end{gathered}[/tex]For the width:
[tex]\begin{gathered} 1\text{ inch}\to15\text{ feet} \\ 2\text{ inches}\to x\text{ feet} \\ \\ \frac{1}{2}=\frac{15}{x} \\ x=15\cdot2=30 \end{gathered}[/tex]Now, calculating the area of the building base, we have:
[tex]\text{Area}=63\cdot30=1890\text{ ft2}[/tex]So the area of the building base is 1890 ft².
