(115+85)*9 = 200 * 9 = 1800
(500+45):5 = 500 : 5 + 45 : 5 = 100 + 9 = 109
(640+60)*7 = 700 * 7 = 4900
(184+116):3 = 300 : 3 = 100
(670+30)*6 = 700 * 6 = 4200
(720+80):8 = 800 : 8 = 100