Leap years normally occur every four years. However, years at the turn of a century are leap years only if they are multiples of 400. Therefore, 2000 was a leap year but the year 1900 was not. How many leap years will there be between 2001 and 3001?

answer: c

substitute in the values.

for a:

f(0) = 0 + 9

f(0) = 9

a is a solution.

for b:

f(7) = 14 + 9

f(7) = 23

b is a solution.

for c:

f (3) = 6 + 9

f(3) = 15

c is not a solution. it's supposed to be 14.

for d:

f(2) = 4 + 9

f(2)= 13

d is a solution.

the easiest way to do these would be to solve the equations. if you can solve the equation than you can solve these problems.

48+y= ?

the y is the variable and the ? could also be a variable  

the answer is a

step-by-step explanation: