take your compass on a point on your line. then draw a circle. take the 2 points in which the circle hit the line and draw 2 circles larger than half the distance between he 2 points. take the point that they intersect and and connect it to the line and you point M and it is purpendicular. does that make sense?
Let
A------------> <span>number of children
B------------> </span><span>number of adults
we know that
0.40A+0.70B=5.90--------------------------> equation 1
A+B=11------------> A=11-B----------------> equation 2
using a graph tool------------> to resolve the equations system
see the attached figure
the solution is
A=6
B=5
the answer is
A is bigger</span>
my best guess would be 13