I think you forgot two signs here:
-9 - 6+12h+40 = 22
(let me know if this is not the case!)\
I'll start left to right, adding the first two numbers:
-15+12h+40 = 22
now, i'll add -15 and 40, which is 25
12h+25 = 22
and subtract 25 from both sides:
12h=22-25
12h =-3
divide by 12:
h =[tex] -\frac{3}{12} [/tex]
h =[tex] -\frac{1}{4} [/tex]
and this is the solution
