The original 2a, and then check (2a+4b) in two days and A+2B in one day;
(2) According to the meaning of the question, 2(a+2b)2=2(a+5b)3.
The solution is a = 4b.
(3)2(a+2b)2÷45b=5(a+2b)4=7.5。
The quality inspection department should send at least 8 inspectors.