let l = lance, and a = alex.
so: l + a = 70
and l = 4a
Putting the value for l in the first equation:
4a +a = 70
5a = 70
a = 14.
So Alex has 14 pencils. And Lance has (70-14) 56 pencils.
And if each child gets half of Alex' pencils, then each child will have 7 pencils.