Answer:
$5.40.
Explanation:
Let the tax on the $90=y
Expressing the problem as a ratio gives:
[tex]\frac{90}{70}=\frac{y}{4.20}[/tex]Solve for y:
[tex]\begin{gathered} y=\frac{90}{70}\times4.20 \\ =5.40 \end{gathered}[/tex]The tax on a $90 item is $5.40.
