plot y%3D1.15*1000*(r*b%2B1)%2C y %3D 1000*(b*r%2B0.5*r%2B1)%2C y %3D 1000*((0.9-r)%2B(b*r%2Bb%2F10%2Br%2B0.1)) from b %3D 0.5 to 6 and r %3D 0 to 1