How would I calculate the percentage?

How would I calculate a percentage for this data:



We are measuring bread mould over a 2 week period. The original measurement of the bread is 12cm x 5cm. By the first day of growth, the mould measured 7cm x 2cm. How would I calculate the percentage of bread that is covered in mould?How would I calculate the percentage?
The equation can be put up as follows:

(Given amount/ Total amount) x100



in your example: (7x2/12x5)x100~23.3%How would I calculate the percentage?
The area of the bread is 60 square cm (12 x 5).

The area of the mold is 14 square cm (7 x 2).



So the percent of the bread that is covered by mold is 14/60.

14/60 = 23.3%.