What is the expression of the product of 4 and a number , then increased by 8.

Really need on these. i have no idea what to do

Jenisey has $24 to spend on seven pencils. after buying them she had $10. how much did each pencil cost.?

The diameter of the moon is about 3500 km. approximate the surface area of the moon using the formula for the surface area of a sphere, s = 4? r^2. write your answer in scientific notation.