Plz I need help with this like now its past due ​

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?

What are two numbers that have a sum of 15?

Candice uses the function f(t)=t+100−−−−−−√ to model the number of students in her after-school program. the variable t represents days and f(t) represents the number of students. how many days does it take for there to be 15 students in her program? a. 225 days b. 125 days c. 325 days d. 115 days