HELP ME PLZ ITS DUE TOMORROW

What are “like terms”? why can we only add like terms?

Desmond wants to sell his car that he paid $8,000 for 2 years ago. the car depreciated, or decreased in value, at a constant rate each month over a 2-year period. if x represents the monthly depreciation amount, which expression shows how much desmond can sell his car for today? \ 8,000 + 24x 8,000 - 24x 8,000 + 2x 8,000 - 2x

Evan went to the park and saw for animals each animal was either a duck or dog if he saw a total of 14 legs how many of each animal did he see