okay i'm currently studying for a ASVAB test for the military. and they have questions like the one below,

"what number is 5% of 2000"

how would i solve for something like that?

or they have

"35% of what number is 70"

"if 45 is 120% of a number, what is 80% of the same number?"

"if 6 is 24% of a number, what is 40% of the same number?"

"25% of $900="

questions like those, please help