Ig=(G+SS)II_{g}=\left(\frac{G+S}{S}\right) IIg=(SG+S)I
Ig=(SG+S)II_{g}=\left(\frac{S}{G+S}\right) IIg=(G+SS)I
Is=(G+5S)II_{s}=\left(\frac{G+5}{S}\right) IIs=(SG+5)I