We have an original annual original budget of $1475. For each month of the year, we have then:
[tex]m=\frac{1475}{12}\approx122.92[/tex]Thus, we have for each month, a monthly budget of $122.92 for spending on social media.
However, in December this budget was increased by 20%, then:
[tex]122.92\cdot\frac{20}{100}=24.58[/tex]Then the budget for the month of December is:
[tex]BD=122.92+24.58\Rightarrow BD=147.5[/tex]