(480+420):20+100:20x4-2        750-(60:10*50)+640:80-70:10        150:5*30-35:5*10+5*10

(480+420):20+100:20*4-2=900:20+100:20*4-2=45+5*4-2=45+20-2=65-2=63750-(60:10*50)+640:80-70:10=750-(6*50)+640:80-70:10=750-300+8-7=450+1=451150:5*30-35:5*10+5*10=30*30-70+50=900-20=880