81-ա,բ,գ,դ, 82-ա,բ,գ,դ, 83, 85, 88։

81 ա) x : 8 = 2 : 1 x = 8 * 2 : 1 = 16 82 ա) x : 4 = 8 : 3 x = 4 * 8 : 3 = 32/3

բ) x : 8 = 6 : 2 x = 8 * 6 : 2 = 24 բ) 7 : x = 9 : 5 , 7 * 5=9 * x , x = 7 * 5 : 9 = 35/9

գ) x : 8 = 2 : 22 x = 8 * 2 : 22 = 8/11 գ) 6 : 17 = x : 3, x = 3 * 6 : 17 = 18/17

դ) x : 8 = 5 : 4 x = 8 * 5 : 4 = 10 դ) 25 : 7 = 15 : x , 25 * x = 15 * 7 , x=15 * 7 : 25 = 21/5

83 3:4 : 1 = 6 : x x = 6 * 3 : 4 = 18/4 = 9/2

88) 160 : 8 = x : 56, x = 56 * 160 : 8 =56 * 20 = 1120

93, 95֊ա,բ, 96, 98, 99։

93) 1005+1005 * 11 : 3 = 1005 + 335 * 11 = 1005 + 3685 = 4690

95) ա) 3/4 : 1/4 + 4*7/2 + 38*11/5 — 3/50 : 1/5 = 4*3 /4 + 7*4/2 + 418/5 + 5*3/50 = 3 + 14 +418/5 +

15/50 = 17 + 4180/50 + 15/50 = 17 + 4195/50 = 17 + 83 + 45/50 = 100 + 9/10 =100.9

բ) (8+3/10-6-2/10)* 11/5 +(6/16-5/16) * 9/5 = (2 + 1/10)*11/5 + 1/16 * 9/5 = 21/10 * 11/5 + 9/80=231/50+9/80=1848/400 + 45/400=1 893/400

98. 1) 640-220=420 2) 3-1=2 3) 420:2=210 4) 640+210=850 = 640 + (640 — 220):2

99) 5*4+5*3+5*7=20+15+35=70 5արկղում միասին