Your classmate showed their thought process to the problem below. However, They made a mistake. What mistake did they make? Describe it below.

Jack has a piece of red ribbon that is two times as long as his piece of blue ribbon. he says that he can use two different equation to find out how long his piece of red ribbon is compared to his piece of blue ribbon is. is he correct? explain his reasoning

Michael is training for a marathon. in his first week he plans to run 8miles. what path should he take

Donald has x twenty-dollar bills and 11 ten-dollar bill. how much money does donald have? write your answer as an expression.