Please help with algebra work

If 20% of a number is 35, what is 50% of that number?

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

Tomas used 3 1/3 cups of flour and now has 1 2/3cups left. which equation can he use to find f, the number of cups of flour he had to begin with? f+3 1/3=1 2/3 f-3 1/3=1 2/3 3 1/3f=1 2/3 f/3 1/3=1 2/3