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diff --git a/2459/CH12/EX12.12/Ex12_12.sce b/2459/CH12/EX12.12/Ex12_12.sce
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+//chapter12
+//example12.12
+//page249
+
+Vcc=15 // V
+Re=2 // kilo ohm
+Rc=1 // kilo ohm
+gain_beta=100
+Vbe=0.7 // V
+R1=10 // kilo ohm
+R2=5 // kilo ohm
+
+Eo=Vcc*R2/(R1+R2)
+Ro=R1*R2/(R1+R2)
+
+printf("thevenin voltage = %.3f V \n",Eo)
+printf("thevenin resistance = %.3f kilo ohm \n",Ro)
+
+// here Eo=Ib*Ro+Vbe+Ie*Re
+// now considering Ie=gain_beta*Ib, and making Ib as subject we get
+// Ib=(Eo-Vbe)/(Ro+gain_beta*Re)
+// Ic=gain_beta*Ib=gain_beta*(Eo-Vbe)/(Ro+gain_beta*Re)
+// dividing numerator and denominator by gain_beta we get
+// Ic=(Eo-Vbe)/(Re+Ro/gain_beta)
+// Ro/gain_beta is negligible compared to Re so
+Ic=(Eo-Vbe)/Re
+Vce=Vcc-Ic*(Rc+Re)
+
+printf("the operating point is %.3f V and %.3f mA \n",Vce,Ic)