(In the third grade, you can also ask six little pandas to help you with the calculation, but in the second grade, you didn't learn the division of 26/2, so you can only use the former method. )
Let's assume that there are 2 red pandas and 2+6=8 giant pandas, making a total of 2+8= 10 pandas. In fact, there are 20 pandas in total, which is 20- 10= 10 more than the hypothesis, which means that there are more pandas 10.
(However, this method of assuming a known number first is estimated that most people are not used to it and will not be used reasonably. )