Question

Please explain fully and i give brainiest thanks and 5 stars

Answer 1

Answer:

$a=7,\\b=3$

Step-by-step explanation:

The area of a rectangle is equal to $A=l\cdot w$, where $l$ is the length of the rectangle and $w$ is the width of the rectangle. In a rectangle, opposite sides are equal.

Therefore, we can write the following system of equations:

$\begin{cases}a\cdot (9+b)=84,\\a\cdot b=21\end{cases}$

Expand the first equation:

$9a+ab=84$

Substitute the second equation into the first ($ab=21$):

$9a+21=84,\\9a=63,\\a=\boxed{7}$

Solving for $b$:

$7b=21,\\b=\frac{21}{7}=\boxed{3}$

Answer 2

Answer:

Step-by-step explanation:

Hope this helps u!!