а) 3,8+х=1 4/5

б)5 2/7+х=-3 9/14

3,8+х = 1 4/5

3,8 = 3 8/10 = 3 4/5

3 4/5+х = 1 4/5

х = 1 4/5 - 3 4/5

х = -2

проверка: 3,8+(-2) = 1 4/5 ; 1,8 = 1,8

5 2/7 + = - 3 9/14

37/7+х = -51/14

х = -51/14-37/7

х= (-51-74)/14

х = -125/14= -8 13/14

проверка

5 2/7 +(-8 13/14) = -3 9/14

74/14-125/14 = -51/14

-51/14 = -51/14

а)3.8+х=1 4/5

х=1 4/5-3.8

х=1 4\5-3 8\10

х=9\4-38\10

х=18\10-38\10

х=-20\10

х=-2

б)5 2\7+х=-3 9\14

х=-3 9\14-5 2\7

х=-51\14-37\7

х=-51\14-74\14

х=-125\14

х=-8 13\14