x/0.3-(0.03+0.05x)/0.02+4=0

x/0.3-(0.03+0.05x)/0.02+4=0

x/0.3-(0.03+0.05x)/0.02+4=0
10x/3-(3+5x)/2+4=0
兩邊同乘以6,得
20x-3(3+5x)+24=0
20x-9-15x+24=0
5x+15=0
5x=-15
x=-3