Which equation equals the first step of substitution in this system of equations?

Norma has an a-frame cabin. the back is shown below. how many square feet of paint will she need to cover the back of the cabin? explain how you found the answer.

While scuba diving, rajeev dove to a depth of 12.6 feet below the surface of the water and then descended another 8.7 feet. what expression can be used to find rajeev's new position? 12.6 – 8.7 –12.6 – 8.7 –12.6 – (–8.7) 12.6 – (–8.7)

Which of the following answers is 5/25 simplified? 1/5 5/5 2/5 1/25