If we know how much money Carly receives every years, we know how much money Carly receives every 12 months.
So, to deduce the money gained in one month, you have to divide by 12:
[tex] 1 \text{ year salary} = 12 \text{ months salary} \implies \dfrac{1}{12}\text{ year salary} = \dfrac{12}{12}=1 \text{ month salary} [/tex]
So, the answer is
[tex] \dfrac{48000}{12} = 4000 [/tex]
