clear
clf
y=@(x)fsolve(@(y)y-(25-(0.0343*x.^2+1.5459*x-0.4413).*(1.965+0.0054*(y-25))),zeros(1,length(x)),optimset('display','off'))
x=linspace(-3,3)
y=y(x)
f1=2*y+1
f2=5*y-7
plot(x,f1,'g')
hold on
plot(x,f2)