The expression is .
Below figure shows the solution using a "TI-84 plus graphing calculator".
Check the solution by substituting n = 37 and j = 19 in the formula .
.
![\"\"](\"/userfiles/image/steps_images/step1.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=dc5227524c4bf4d88f6e8a0f8b6752fc.png\")
.![\"TI-84](\"/userfiles/image/Library/Pre%20Calculus/TI-84_graphing_calculator_37_nCr_19.gif\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=b03b258d0e0e46fc013f9c5f8916f923.png\")
![\"\"](\"/userfiles/image/steps_images/step2.JPG\")
![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=c3eeade52ab959df19db8a5ddcaf6d9e.png\")
. ![\"\"](\"/test/fckeditor/editor/plugins/fckeditor_wiris/integration/showimage.php?formula=c3f3aeb0cb4ceb801090b338b028c6e0.png\")
![\"\"](\"/userfiles/image/steps_images/solution.JPG\")
.