#### Explanation:

A drop of 20 % means find 80% = $\times 0.8$
An increase of 10% means find 110% = $\times 1.1$

Let the original price be $x$. We can follow what was done to this price in the form of an equation.

Decreased by 20% then raised by 10%..

$x \times 0.8 \times 1.1 = 70.40 \text{ }$ Now just solve for $x$

x = 70.40/(0.8 xx1.1

=\$80