Hmmmm.... your answer was one that the author didn't anticipate.
Before solving this problem, check to see that you've copied it accurately: Be certain that the numerals and operation signs are EXACTLY THE SAME as the ones in the original.
Follow the correct order of operations and then double-check your arithmetic.
Please carefully copy and solve this problem on your paper:
Order of Operations Automatic Flip-Through SLIDE SHOW
Overview of the Order of Operations
© 1992, 1999 Amby Duncan-Carr All rights reserved.