设总钱数Ma,等额本息还款,月息Pm,每月还x,其中包括的本金为y1,y2,...
x=Ma*Pm+y1=(Ma-y1)*Pm+y2=...
y2=y1*(1+Pm)
y3=y2*(1+Pm)=y1*(1+Pm)^2
...
到最后一个月还完
Ma-y1-y2-...yn-1=0
Ma=y1*(1+(1+Pm)+(1+Pm)^2+...+(1+Pm)^(n-1))
=y1*((1+Pm)^n-1)/((1+Pm)-1)=y1*((1+Pm)^n-1)/Pm
y1=Ma*Pm/((1+Pm)^n-1)
x=Ma*Pm(1+1/((1+Pm)^n-1))
3000=Ma*0.005*(1+1/(1.8194-1))
Ma=270220.95