Can someone me on this one problem?

From the beginning of the day the temperature rose 15 degrees so that by 4 pm it was 87 degrees. what was the temperature at the start of the day

How many quarts of a 50% solution of acid must be added to 20 quarts of a 20% solution of acid in order to get a 40% solution of acid?

Situation: . find the substance's half-life, in days. round your answer to the nearest tenth. a 11 gram sample of a substance that's used to treat thyroid disorders has a k. value of 0.1247. enter the correct answer n - noekt done no - initial mass (at time t = 0) n - mass at timet k a positive constant that depends on the substance itself and on the units used to measure time t= time, in days