Question

Mckenzie's age is 3 years less than 4 times Alec's age. Lily is 1 year less than Mckenzie. If Alec is 2, how old is Lily?

Answer 1

m = 4 a - 3
so
m = 4 (2) - 3
m = 8 - 3
m = 5
then
L = m-1
L = 4

Answer 2

You did not have to ask me because you could have checked your answer of 4 easily.
Just use 4 for lily and go back to the text of the question.
If Lily is 4 then McK must be 5
If McK is 5 then McK +3 is 8 which is four times Alec so Alec must be 2. Sure enough, that is right.