.
Joe + Sally = = 78.
It is the same as to say
Joe + (Joe + 2) = 78.
It is the same as
2*Joe = 78 - 2
2*Joe = 76
Joe = 76/2 = 38.
Answer. Joe has 38 jelly beans. Sally gas 2 more, i.e. 38+2 = 40 jelly beans.
-------------
Dear tutors, as you read the problem, you should understand from the tone, in which it is written,
that the problem is designed and intended for very young students (4-5 grades), who DEFINITELY don't know
and do not understand what is the system of algebraic equation. Therefore, the solution for them should be appropriate !