Find the Slope Of The A and B

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)

Ineed me i stuck and i don’t want to get it wrong

The ph level of a blueberry is 3.1 what is the hydrogen-ion concentration [h+] for the blueberry