25% of what number equals 100

What is the inverse of the function f(x)=2x+1

Find the number of positive three-digit even integers whose digits are among 9, 8, 7,5, 3, and 1.

Elena and her husband marc both drive to work. elena's car has a current mileage (total distance driven) of 15,000 and she drives 23,000 miles more each year. marc's car has a current mileage of 46,000 and he drives 9,000 miles more each year. will the mileages for the two cars ever be equal? explain.