The amount can be calculated using the formula
[tex] A=P( 1+\frac{r}{100})^t [/tex]
Here P is the Principal ,r is the rate of interest and t is the formula .
In the given question P=$1200 ,r=5% ,t= 4 years.
Substituting these values in the formula
[tex] A=1200( 1+\frac{5}{100} )^4 [/tex]
[tex] A=1200(1.05)^{4} [/tex]
A=1458.60
Amount of monthly payment=[tex] \frac{1458.60}{12} =121.55 [/tex]
The amount of your monthly payment is $121.55.