Find the Length of segment XY

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)

Taking algebra two apex courses and need with these questions

Determine the difference: 3.2 × 1010 – 1.1 × 1010. write your answer in scientific notation.