First write what are given from the question
We write "Craig scored 12 points in a game" as
⇒ c = 12 (first equation)
We write "Marla scored twice as many points as Craig but 5 fewer than Nelson scored" as
⇒ m = 2c (second equation)
⇒ m = n - 5 (third equation)
Second, find the expression for n based on what we write above
From the second and third equation
⇒ m = m
⇒ n - 5 = 2c
Subtitute from the first equation
⇒ n - 5 = 2c
⇒ n - 5 = 2(12)
⇒ n - 5 = 24
This is the expression to find how many nelson scored
n - 5 = 24