145 – 6 * 15 : 18 = 145 - 90 : 18 = 145 - 5 = 140
640 : 8 – 4 * 5 = 80 - 4 * 5 = 80 - 20 = 60
240 : (4 + 6) * 2 = 240 : 10 * 2 = 24 * 2 = 48
(560 : 7) : 40 * 1 = 80 : 40 * 1 = 2 * 1 = 2