Mathematics from grade 5-6, how to calculate the percentage?

Question

Mathematics

Hello! At night, apparently, the brain doesn’t work at all, or I’m dumb (more likely), I can’t draw up a formula for calculating percentages, namely: there is an old number, you need to find out how many percent will remain in it from the original state if we reduce it by a new (smaller) number ?

Thanks in advance!

Answer 1

9000 - 100%
6000 - x%
x = 6000 * 100 / 9000 = 66.666666667
i.e. 6000 is 66.666666667% of 9000
i.e. 9000 decreased by (100 - 66.666666667) = 33.333333333%.