How do I solve this using substitution?

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)

Afunction, f(x), represents the height of a plant x months after being planted. students measure and record the height on a monthly basis. select the appropriate domain for this situation. a. the set of all positive real numbers b. the set of all integers oc. the set of all positive integers od. the set of all real numbers reset next

If it 8 inch candle burns at 7/10 inch per hour and a 6 inch candle burns at 1/5 inch per hour after how many hours would both candles be the same height