bantu mengerjakan no 1-7

-20+8×5-18:-3
=-20+40-18:-3
=-20+40+6
=-20+46
=26


3×12×3000
=36×3000
=108000
maka 108000-90000=18000
90000×20%
=90000×20/100
=18000
maka 18000=20%