Question

What is x? 5a 4a 90 O 9 O 100 80

Answer 1

In this case, we can wee that

$5a+4a=\text{ 180}$

hence,

$\begin{gathered} 9a=180 \\ a=\frac{180}{9} \\ a=20 \end{gathered}$

On the other hand, we can also see that

$x+4a=180$

since a=20, then

$\begin{gathered} x+4(20)=180 \\ x+80=180 \\ x=180-80 \\ x=100 \end{gathered}$