tolong bantuin jawab soal cerita no20-22 yaa! :)

20. B(x) = 1600x + 350000(7hari)
= 1600x + 2450000

21. I = 1600k + 350000
II = 900k + 500000

1600k + 350000 = 900k + 500000
700k = 150000
k = 1500/7

22. II = 900k + 500000(3hari) = 1635000
900k + 1500000 = 1635000
900k = 135000
k = 150