Answer:
[tex]4\cdot x=45[/tex]
Step-by-step explanation:
We have been given a proportion [tex]\frac{4}{5}=\frac{9}{x}[/tex]. We are asked to find the equation that could be used to solve for x.
To solve for x we will cross multiply our given equation as:
[tex]4\cdot x=5\cdot 9[/tex]
[tex]4\cdot x=45[/tex]
Now we will divide both sides of our equation by 4 as:
[tex]\frac{4\cdot x}{4}=\frac{45}{4}[/tex]
[tex]x=11.25[/tex]
Therefore, the equation [tex]4\cdot x=45[/tex] could be used to find the value of x.