..Supposed the point (2,4) is on the graph of y=f(x). Find a point on the graph of the given function

1) y=f(x+1) Mr F says: Substitute x = 1 and what have you got ....?

a)(2,3)

b) (1,4)

c) (2,5)

d) (3,4)

2)y=f(x)+8 Mr F says: Substitute x = 2 and what have you got ....?

a) (2,-8)

b) (-6,4)

c) (2,12)

d) (10,4)

Im not looking for the answer, but rather how to solve the problems. I can't find a similar one in my book.