7th grade math
posted by kelly .
jess, marie, and emily are sisters. The sum of their ages is 118. Emily is twice jess's age. Jess is 7 years older than Marie. How old is each girl?

E+M+J=118
2J+J7 +J=118 
Hi Bob, I got that part but I still can't figure out how old each one is
help 
Hi Bob , I got that part but I still can't figure out how old each one is , or rather I believe I know the answers
jesse 31.25 emily 62.5 & marie 24.25
The problem I have is breaking that formal down to a simply equation and I can't figure it out