Seems easy, i know, but apparently, the answer is incorrect all the time. any ?

do the white circles multiplied by the white shapes to get the fraction of white circles:

3/10 = fraction of ratio of white circles

5/16 = ratio of white shapes

3/10 × 5/16 = 15/160 (white circles)

do the same for the black circles:

3/11 = ratio of black circles

11/16 = ratio of black shapes

3/11 × 11/16 = 33/176 (black circles)

then you must add these fractions together:

15/160 + 33/176

(to make this easier you can simplify them first)

3/32 + 3/16

multiply second fraction by 2 to get the lowest common denominator of 32

3/32 + 6/32

= 9/32

answer = 9/32 (total circles)

The word "cover" indicates it is the area that we are looking for.
area of the top: 13*9=117
area of the bottom:117
area of the front side: 13*3=39
area of the back side: 39
area of the right side: 9*3=27
area of the left side: 27
add them all up: 117+117+39+39+27+27=366
No, one can is not enough to cover the whole cake.

Please use a calculator to double check my calculations