In each equation, the ? represents an operation. Which operation makes each equation true?

In football, the team that has the ball has four chances to gain at least 10 yards. If they don't gain at least 10 yards, the other team gets the ball. Positive numbers represent a gain of yards, and negative numbers represent a loss of yards. The Bulldogs just got the ball. Select all the sequences of four plays that result in the Bulldogs getting to keep the ball.

A sandwich store charges $20 to have 3 turkey subs delivered and $26 to have 4 delivered.

1. Is the relationship between the number of turkey subs delivered and the amount charged proportional? Explain how you know.
2. How much does the store charge to deliver 1 additional turkey sub?
3. Describe a rule for determining how much the store charges based on the number of turkey subs delivered.

Which question cannot be answered by the solution to the equation ?