№1.
Д(32) = {1, 2, 4, 8,16,32}
Д(42) = {1, 2, 3, 6, 7,14, 21, 42}
ОД ( 32 , 42 ) = {1,2}
Д (54) ={1,2,3,6,9,18, 27,54}
Д (72) = {1,2 ,3,4, 6, 8, 9, 18, 12, 24, 36, 72}
ОД (54,72)= {1,2,3,6,9,18}
Д (96) = {1, 2 , 3, 4, 6, 8, 12, 16,24,32,48,96}
Д (40) = (1,2,4, 5, 8, 10, 20,40}
ОД (96,40) = {1, 2, 4, 8 }
№2.
НОД (32,42) = 2
НОД (54,72) = 18
НОД (96,40) = 8
№3.
32/42 = 16/21
54/72 = 3/4
96/40 = 12/5 = 2 2/5
№4.
а) 22,8 / 5,7 = 228/57 = 4
б) (3 1/8 ) / (1 1/4) = 25/8 : 5/4 = 25/8 * 4/5 =
=(25*4)/(8*5) = (5*1)/(2*1) = 5/2 = 2 1/2 =2,5
в) числитель:
4,8 - 5 2/5 : 1 4/5 = 4,8 - 5,4:1,8 = 4,8- 3 = 1,8
знаменатель:
2,4 * ( 7/8) * 1,5 = 2,4*0,875*1,5 = 3,15
получается дробь:
1,8 / 3,15 = 180/315 = 4/7