What is the upper and lower bound of #c/a - b/d#?

If:
#a=5.6# (#1# d.p)
#b=24.1# (#1# d.p)
#c=145# (#3# s.f)
#d=0.34# (#2# d.p)

I got two different answers using two different ways when doing this question.. #-46.5# and #-45.2# for the lower bound, and #-43.5# and #-44.8# for the upper

When I did it the first time I made the the "equation" into one fraction, #(cd-ba) /(ad) #, through this I took the lower bound of #cd# #[48.4075]#, upper bound of #ba [136.4475]# and upper bound of #ad [1.94925]# to find the lower bound of the answer, as well as the reverse to find the upper bound.

For checking I did it the "normal" way and just took the lower bound of #c/a##-# the upper bound of #b/d#, to find the lower bound of the answer, and the reverse for the upper bound...

I am sooo confused... Any help would be greatly appreciated