SOLUTION: Subtract 3.1X + 1.8 from 4X - 5 Choices given (A) 0.9x-3.2 (B) 0.9x-6.8 (C) -0.9x+6.8 (D) -0.9x-3.2 I would like to know if I have the correct answer. I picked (B) 0.

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Subtract 3.1X + 1.8 from 4X - 5 Choices given (A) 0.9x-3.2 (B) 0.9x-6.8 (C) -0.9x+6.8 (D) -0.9x-3.2 I would like to know if I have the correct answer. I picked (B) 0.      Log On


   

Question 295406: Subtract 3.1X + 1.8 from 4X - 5
Choices given
(A) 0.9x-3.2
(B) 0.9x-6.8
(C) -0.9x+6.8
(D) -0.9x-3.2
I would like to know if I have the correct answer.
I picked (B) 0.9x-6.8
4X-5 - (3.1x + 1.8)
4X - 5 - 3.1x - 1.8
4x -3.1 = 0.9x -5 - 1.8 = -6.8
answer: 0.9X-6.8

my teacher worked it out and came up with 2 different answers. the first time she put 4X-5-3.1X+1.8. then she said worked it the way I did with the parentheses around the 3.1x + 1.8 making both negative numbers. Since half of the class is confused and they disagree with my answer, I would like to know if I solved this problem correct.
thank-you! :)
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
Do this the same as any subtraction but term by term .
4X   - 5
3.1X + 1.8 

4.0X - 5.0
3.1X + 1.8 

 .9x - 6.8

If you are subtracting 4x-5 from 3.1x+1.8 the answer is different
3.1x+1.8
4x   -5
-.9x+6.8

You need to do something about this teacher.
What level are you? grade school, high school, college?
Students should not be able to persuade a teacher to change answers nor methods.
There probably isn't much chance of doing anything in grade school. But if this is a middle school, high school or higher, the teacher is unqualified.