See: http://www.electronics-tutorials.ws/resistor/res_3.html Ex 1: 1 2 6 s s Answer: 9 ohms See: http://www.electronics-tutorials.ws/resistor/res_4.html Ex 1: 200 470 p 220 p Answer: 85.67 ohms See: http://www.electronics-tutorials.ws/resistor/res_5.html Ex 1: 8 4 s 12 p 6 s Answer: 12 ohms Ex 2: 10 2 s 6 p 8 s 6 p 4 s 8 p 4 s 8 p 6 s Answer: 10 ohms