tolong di bantu ya soal hukum newton dan gaya gesek kelas 10 sma

[tex]\displaystyle w_a=100\,\text{N}\\w_b=500\,\text{N}\\\mu_{a,b}=0,2\\\mu_{b,l}=0,5\\\\F=?\\\\\Sigma F=0\\F-f_{a,b}-f_{b,l}=0\\F=f_{a,b}+f_{b,l}\\F=\mu_{a,b}w_a+\mu_{b,l}(w_a+w_b)\\F=0,2\cdot100+0,5(100+500)\\F=0,2\cdot100+0,5(600)\\F=20+300\\\boxed{\boxed{F=320\,\text{N}}}[/tex]