<PRE><B>Question 578562</B>
5b+7+2b=23
combine like terms first: 5b+2b=7b
what it should look like: 7b+7=23

now subtract 7 from 23 since you add it to help find b: 7b+7-7=23-7
what it should look like: 7b=16

now divide 16 by 7 to find b: 7b/7=16/7
b=2 2/7
or 
16 over 7

check: plug in b to solve-
5(2 2/7)+7+2(2 2/7)=23
80 over 7+7+32 over 7= 23
23=23 :D

ps (when i use / it means over)</PRE>