#1
75+40 = 115 коров стало
184/x = 115/75
184*75 = 115x
13800 = 115x
x = 120
Корма хватит на 120 дней
#107
3) (2,7)/9 = (1 1/5)/(3x+1)
2,7(3x+1) = 9*1 1/5
8,1x+2,7 = 54/5
8,1x = 81/10
x = 1
5) 6/(1 4/5) = (3x+0,6)/(2,88)
6*2,88 = 1 4/5*(3x+0,6)
17,28 = 5,4x+1,08
16,2 = 5,4x
x = 3