All you have to do is isolate b on the right side. Here is how you do it:
74=2b+5
First subtract 5 from each side
74-5=2b+5-5
Now simplify
69=2b
Now to get b by itself, divide both sides by 2
69/2= 2b/2
Now simplify:
34.5=b
To check, plug it in to the original equation:
74= 2(34.5)+5
74=74