If 25 of a number is 780 then what percent of 520 is the number ........

Explanation:

Let the number be x.
Then, 25% of x = 780
(25/100)x = 780
x = 3120
Now, let y% of 520 = 3120
Then, (y%)520 = 3120
y = (3120)/520
y = 6%