The equation is .
Observe the 4 steps, third step is wrong, since it is wrong simplification
The second step is .
Subtract 20 from each side.
, This is the correct third step.
The option B is correct answer.
![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=eb9f0cb34fc27a99c913ffc6d0368d7d.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=eb2b4c80a03b5e597fab2232545f2992.png\")
.![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=6317616d442d1f895fd31f64c2e4e721.png\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=82336208f2c53860785f74ce729c75ac.png\")
, This is the correct third step.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")