Answer:
I'm assuming you're learning how to simplify and solve algebraic expressions. This is a word problem? In any case, in 6+t=20 you're trying to isolate the variable, t. It makes more sense to subtract 6 from both sides of the equation. On the left side, subtracting 6-6 = 0, leaving us with t, and if we subtract 6 from 20 (remember you have to do the same thing on both sides), you get 14. Therefore, t = 14.
I'm trying to make of it what the word problem is trying to say. You could subtract 20 from both sides, but it's not going to leave you with an isolated variable, and then you'll get negative numbers involved unnecessarily. Colins reasoning (if it means that he came up with that equation simply based on Marge's "subtracting 20 from both sides of the equation to solve it), doesn't make sense to me at all. I would say his reasoning does not make sense, because of all I explained above. I hope that helps even just a little. I feel like something else is missing from the question.
Step-by-step explanation:
