Get:

30- 10x=20-5x (length of thin candle after burning for x hours = length of long candle after burning for x hours)

Transferred items:

5x= 10

x=2

Two hours later, the two candles are the same length. Answer 2: If you don't take all the solutions, you might as well tick (a? 0? 5-4)=-a？ 0? 5[√a-√(b- 1)]=0, then a = 2a = 2, -2 is discarded because √(-2) is meaningless. Answer 3: Suppose there are X products in each box.

Then an A machine produces (8x+4)/5 products every day.

Machine a and machine b produce (1 1x= 1)7 products every day.

As we all know, each type A machine produces one more product every day than the type B machine.

Then the countable equation is (8x+4)/5-(11x =1) 7 =1.

The solution is x= 12.

So each box contains 12 products.