-7 1/2m+2 2/3m+1/6m=1 3/4•(-2 1/3)+4 1/5•2 5/6

-7 1/2m + 2 2/3m + 1/6m = 1 3/4•(-2 1/3) + 4 1/5•2 5/6
-15/2m + 8/3m + 1/6m = -7/4•-7/3 + 21/5•17/6
-30/4m + 32/6m + 1/6m = 49/12 + 357/30
-15/2m + 16/2m + 1/6m = 49/12 + 119/10
-28/6m + 1/6m = 49/12 + 119/10
-27/6m = 49/12 + 119/10
-9/2m = 49/12 + 119/10
-9/2m = 245/60 + 357/30
-9/2m = 1225/300 + 714/150
-9/2m = 1225/300 + 2142/300
-9/2m = 3367/300
m = -672/300
m = -56/25

Ответ: m = -56/25