x(x-3%)=6000
x^2-0.03x=6000
(x-0.015)^2=6000+0.015^2
x-0.015≈±77.460
x≈0.015±77.460
x1≈0.015-77.460=-77.445
x2≈0.015+77.460=77.475谢了！