If the area of a circle is 64 square meters then what is the radius

Phillip had some bricks. he stacked them in 6 equal piles. which expression shows the number of bricks phillip put in each pile? let the variable m stand for the unknown number of bricks. m + 6 m÷6    m−6    6m

Which expression do you get when you eliminate the negative exponents of 4a^2 b^216a^-3 b

Answer pls man im trying to get out of summer school