program Subroutines
implicit none
real*8 :: a, b, c, d
a=3d0
b=5d0
call addIt(a,b)
c=10d0
d=2d0
call addIt(c,d)
contains
subroutine addIt(a,b)
implicit none
real*8, intent(in) :: a,b
real*8 :: c
c=a+b
write(*,*)a,'+',b,'=',c
end subroutine
end program