Answer:
I would model and record finding the sum and difference of two rocks by calculating the weight and pound and it will be equal to the mass of that rock.
Step-by-step explanation:
First you would distribute the 3. So it would be (3x+6)+14+7x. Since you can’t do anything inside the parentheses, you drop them. Then you’d combine like terms. 3x+7x is 10x, and 14+6 is 20. That would get you your answer, 10x+20