The current mortgage rate is 11%
the total value of mortgage is:
[tex]\begin{gathered} 180000+11\text{ perstnage of 180000} \\ 180000+19800 \\ =199800 \end{gathered}[/tex]Required down payment is 20% then:
20% of 199800
[tex]\begin{gathered} \frac{20}{100}\times199800 \\ =39960 \end{gathered}[/tex]Total monthly payment for 25 year
[tex]\text{monthly payment=}\frac{total\text{ value-required down payment}}{\text{time (in month)}}[/tex]So the value of monthly payment is:
[tex]\begin{gathered} \text{monthly payment}=\frac{199800-39960}{25\times12} \\ =\frac{159840}{300} \\ =532.8 \end{gathered}[/tex]The required down payment is 39960 and monthly payment is 532.8.