Mary and Amy had a total of 20 yards of material from which to make costumes. Mary used three times more material to make her costume than Amy used, and 2 yards of material was not used. How many yards of material did Amy use for her costume?
MY SET UP:
Let M = Mary
Let A = Amy
M + A = 20 yards
3M + A = 18 yards
I equated 3m + A to 18 because the question stated that 2 yards were not used.
Is this the correct group of equations or is the entire set up wrong?
Creating proper equations for given word problems is the main difference between students of math and math professionals like the tutors on this site. I have not been able to set up the right equations for questions since I started pre-calculus (and before this course). The course has two more semesters because we started in August.