What is the overall purpose of photosynthesis ?

The primary function of photosynthesis is to convert solar energy into chemical energy and then store that chemical energy for future use.

Find out the  what was the original price of her purchase .

To prove

Let us assume that the original price of her purchase be x.

As given

A store is having a 20%-off sale on all merchandise. If Mai buys one item and saves $13 .

20% is written in the decimal form.

= 0.20

Than the equation becomes

x × 0.20 = 13

x = $65

Therefore the original price of her purchase is $65.