First, write an equation that relates the numbers and variables that you were given.
n=first locker
N=second locker
N=n+1
147=n+N
147=n+(n+1)
147=n+n+1
147=2n+1
146=2n
73=n
Now that you have found the first number, you can find the second one by using the equation we created.
N=n+1
N=73+1=74
