8. (6 points) Look at the picture and fill in the numbers



Translate the text above into English, please retain the line breaks and format of the source text, and output the translation result directly.
【Solution】Solution: 1 apple's mass + 2 pears' mass $=1600$ grams $\cdots$ (1), 3 apples' mass + 2 pears' mass $=2800$ grams…(2), 
(2) - (1) can get:
$3-1$ apples' mass $=2800-1600$
2 apples' mass $=1200$
1 apple's mass $=600$
Answer: 1 apple's mass is 600 grams.
Therefore, the answer is: 600.