Question

7. Ms. Vickory assigned the problem: 8/9-4/6. Three of her students' responses are below. Who completed the problem correctly? What common mistakes did the other two students make?

The three students
Sue- 8/9-4/6=4/3 or 1 1/3
Jim- 8/6 - 4/6 = 48/54 - 36/54= 12/54 or 2/9
Bob- 8/9- 4/6 = 8/54-4/54= 4/54 = 2/27

Answer 1

Jim: 2/9

Explanation:

8/9-4/6

48/54-36/54 [Convert each fraction to a common denominator: 54

Multiply (8/9)*(6/6)=48/54; Multiply (4/6)*(9/9) = 36/54]

48/54-36/54 = 12/54

12/54 can be reduced to 2/9

Jim also has 2/9

Sue- 8/9-4/6=4/3 or 1 1/3: Sue subtracted both the numerator and denominator. This is not correct.

Jim- 8/6 - 4/6 = 48/54 - 36/54= 12/54 or 2/9: Good Job Jim

Bob- 8/9- 4/6 = 8/54-4/54= 4/54 = 2/27: Bob converted both denominators to 54, but did not multiply the numerators by the same numbers. Bad Bob.