#1. 10-15/(3)(6)-12

#2. 11-15/(6)(4)-18
this is what i come up with
#1 -4/24-18=-4/6
#2 -5/18-12=-5/6

From you notation, it is not clear whether the denominator is just the first of the two terms or both of them. I will first assume it is just the first number.

[10-15/(3)] (6) -12 = (-5/3)(6) - 12 = -10 - 12 = -22

Now if it is both numbers.

[10-15/(3)(6)] -12 = -5/18 - 12 = - 5/18 -216/18 = -221/18

Decide on your denominator and go through the same processes for the second problem.

I hope this helps. Thanks for asking.