Terminating a conversation

LaTeX: \sum Ma=Mp\:and\:after\:I\:got\:the\:numbers\:I\:did\:\sum Ma=-Mf\:to\:get\:answer\:can\:anyone\:tell\:me\:if\:I'm\:doing\:it\:right∑ M a = M p a n d a f t e r I g o t t h e n u m b e r s I d i d ∑ M a = − M f t o g e t a n s w e r c a n a n y o n e t e l l m e i f I ′ m doing rigth ?