Let us simplify first:
h-h is zero and 5+1=6
so (0 + 1)/4 = (2h + 3)/6 or 1/4 = (2h + 3)/6
Multiple both sides by 4 so 1 = 4(2h + 3)/6
now multiple both sides by 6 and simplify:
6 = 8h +12 subtract 12 from both sides
-6 = 8h divide both sides by 8
-6/8 = h reduce -3/4 = h