ok..heres it..
that ":" means "such that"...its dere in the book..read it.
k..so..
solve the inequalitites in both the sides to get
(15-2x>=7) n (5x-2>10-x)
solve them
(x<= 4) n (x>2)
now the left hand side values can be... 4,3,2,1,0 and so on
right hand side.. 3, 4, 5 and so on
the intersection is (3,4)