What is the missing reason in step 7

What is the volume of the sphere shown below with a radius of 3?

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4

Marco has $38.43 dollars in his checking account. his checking account is linked to his amazon music account so he can buy music. the songs he purchases cost $1.29. part 1: write an expression to describe the amount of money in his checking account in relationship to the number of songs he purchases. part 2: describe what the variable represents in this situation.