Tolong jelasin cara jawabnya beserta rumusnya!plis

1.(18x15) + (15x20) + (12x25) = 270+300+300 = 870/20 = 43½ per orangnya

2.Kayu= 9x45000 = 405000
asbes = 8x28000 = 224000 + = 629000

sisa uang = 700,000 - 629,000 = Rp. 71,000