Using the formula of Compound interest: A=p(1+R/100)^n
A=27780(1+(15/100))^3 =x(1+(15/100))^2+x(1+(15/100))^1+x
27780(1+(15/100))^3 =x(1+(15/100))^2+x(1+(15/100))^1+x (taking x as common)
27780(1+(15/100))^3 =x(3.4725)
x=42249.9075/3.4725
x =12167 (amount )