а) (15-30)-(10-20) = -15 -(-10) = -15 +10 = -5
б) (40-70)-(15-45) = -30 -(-30) = -30 +30 = 60
в) (1-19)-(31-41) = -18 -(-10) = -18 +10 = -8
г) (-45+10)-(-8-0) = -35 -(-8) = -35 +8 = -27
д) (219+511)-(-89+219) = 730 -130 = 600
е) (625+139)-(325+139) = 764 -464 = 300
ж) (218-425)-(18-435) = -207 -(-417) = -207 +417 = 210
з) -(29+109)-(378-78) = (-29-109)-300 = -138 -300 = -438
и) -(8×9 + 3×7 -68) = -(72+21-68) = -(93-68) = -25
к) -(8×12 - 4×9 -56) = -(96-36-56) = -(96-92) = -4
л) (20-(-6)) - (15-(-12)) = (20+6) - (15+12) = 26 - 27 = -1
м) -29-(18-74)-(74-19) = -29 -(-56)-55 = -29 +56 -55 = -28