2.51 in expanded and word form

Overall, George's financial outcome is a gain of $20.  

Step-by-step explanation:

George invested $50 into his tree, which put him at a loss of -50.  When he first sold the tree for $60, he made an overall profit of $10, or -50+60=10.  When he bought back the tree, he spent another $70, or -70 which left him with an overall debt of $60, or 10-70= - 60.  The second time he sold the tree for $80, he made an overall profit of $20 given that his investment in the tree was then at -60 and he sold the tree for $80, or -60 + 80 = 20.