60k,40k並聯,60k⫽40k=24kΩ
24k,16k,10k串聯=24k+16k+10k=50kΩ
150k,50k並聯,150k⫽50k=37.5kΩ
20k,37.5k,2.5k串聯=20k+37.5k+2.5k=60kΩ