What is a percent? doesn't it mean a fraction out of 100?

How much dextrose 70% must be mixed with dextrose 5% to prepare 1,000 ml of dextrose 20%?

35 ! insert < , > , or = to make the sentence true. 12 __ 25 > =

Gables properties corp. is leasing office building with an area of 49b^2+70b+25. what is the shape of the building? a) rectangle b) square