Question

if the area of the rectangle is 90km^2, then what is the value of the missing side

Answer 1

The area of a rectangle is given by:

$\begin{gathered} A=w\cdot h \\ \end{gathered}$

Where:

w = width

h = height = 9km

A = Area = 90km²

so:

$\begin{gathered} 90=9\cdot w \\ \text{solve for w:} \\ w=\frac{90}{9} \\ w=10\operatorname{km} \end{gathered}$