Ok. Let's do this.
So for the first question, ( 3x + 6 = 24) just subtract 6 from both sides. Now we have ( 3x = 18). Now we just need to simplify it and divide both sides to find what x equals. Divide by 3 and we get X = 6
Second question is similar except we need to multiply every single number there by 4 to make x not a fraction. So now we have (X + 4 = -20) Just like last time, we're gonna subtact 4 from both sides. That leaves us with X = -24
3rd question. This one was a little more difficult for me. So we know that they sold 396 watermelons and cantaloupes and that they sold 126 more watermelons than they did cantaloupes. This does NOT mean that they sold 126 watermelons. It just means that they sold 126 MORE. So the correct formula for that question would be the last one, (2n + 126 = 396) To actually find out we would use that formula and subtract 126 from both sides and that leaves us with (2n = 200). Divide both sides by 2 and we find out that they sold 100 cantaloupes. Now don't forget that they sold 126 MORE watermelons than they did cantaloupes so we need to add 126 to 100. So they sold 126 watermelons and 100 cantaloupes. I hope that helps! I tried to write it in a way that made as much sense as possible.