We know that 1600 is an unknown percent of 6400, so we can write it down as:
1600 = x% from 6400
1600 = x/100 * 6400
1600 = x * 64
1600 = 64x / ÷ 64 (both sides)
x = 25
Doublecheck:
6400 * 25% =
= 6400 * 25/100 =
= 6400 * 1/4 =
= 6400/4 =
= 1600, so it's correct ;)
