The answer is x=3.6 or 3 3/5.
First we convert the decimal answer to a fraction; 0.9 is read as "nine tenths," so the corresponding fraction is 9/10:
1 5/6 - (x - 7/12) + 2 1/12 = 9/10
Now we find a common denominator. The first thing that 6, 12 and 10 will all divide into is 60:
1 50/60 - (x - 35/60) + 2 5/60 = 54/60
Distributing the negative, we have:
1 50/60 - x + 35/60 + 2 5/60 = 54/60
Combining like terms, we have:
-x + 4 30/60 = 54/60
Subtracting 4 30/60 from each side, we have:
-x + 4 30/60 - 4 30/60 = 54/60 - 4 30/60
-x = -3 36/60
Divide both sides by -1:
-x/-1 = (-3 36/60)/-1
x = 3 36/60 = 3 3/5 = 3.6
