6y+9y-5y please help me

Can someone me with my hwplz(only the circled ones)

Use the radius you found in part i (r=26.8 cm) with the surface area formula below to find the surface area of the sphere. show your work and round your answer to the nearest tenth. the surface area of a sphere: sa = 4πr^2 self note: 3.8.4

Find the multiplicative inverse of 8-12i