1,(3800-3500)×3%=92,Y=(X-3500)×3%① (3500≤X≤4000) =(X-4000)×10%+500×3%② (4000<X≤5500) =(X-5500)×20%+1500×10%+500×3%③ (5500<X≤16500)3,Y=300带入方程中300=(X-5500)×20%+150+15解得X=6175