3out of 20 boxes are damaged what percent is damaged?

'out of' generally indicates division

So 3 out of 20 boxes, is basically the same as 3 ÷ 20.

3 ÷ 20 = 0.15

To work out the percentage, you have to multiply this value by 100 (per CENT, cent means 100 in Latin).

0.15 × 100 = 15%.

The answer is 15% of the boxes are damaged. 

I’m not absolutely sure but i think it’s 7x6x5x4x3x2=5040 because as the first character you can take any of the 7 given then you are left with 5 then 6 then 4 etc.