(120-70)÷10+186 = (50)÷10+186 = 5+186 = 19628-4000÷100+9 = 628-40+9 = 588+9 = 59(450÷5+80)÷10 = (90+80)÷10 = 170÷10 = 1580-270÷(900÷100) = 580-270÷9 = 580-30 = 550
(120-70)÷10+186 = (50)÷10+186 = 5+186 = 19
628-4000÷100+9 = 628-40+9 = 588+9 = 59
(450÷5+80)÷10 = (90+80)÷10 = 170÷10 = 1
580-270÷(900÷100) = 580-270÷9 = 580-30 = 550