What is the inverse of the fuction f(x)=19/x

You work for a lender that requires a 20% down payment and uses the standard depth to income ratio to determine a person‘s a little eligibility for a home loan of the following choose the person that you would rate the highest on their eligibility for a home loan

Can someone me do math because i am having a breakdown rn because i don’t get it

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?