Help??? what us the exponent of x and y???

Write an explicit formula that represents the sequence defined by the following recursive formula:

The difference of 2 numbers is 21 and the quotient of the equation is 4 then what are the two numbers?

White shapes and black shapes are used in a game. some of the shapes are circles. while the rest are squares. the ratio of the number of white shapes to the number of black shapes is 5: 11. the ratio of the number of white cicrles to the number of white squares is 3: 7. the ratio of the number of black circles to the number of black squres is 3: 8. work out what fraction of all the shapes are circles.