Let
x-------------------> Paul earns tips
y-------------------> Colin earns tips
z-------------------> Brian earns tips
we know that
x+y+z=£71.10
and
the ratio is 2:3:4
therefore
x/y=2/3 x/z=2/4 y/z=3/4
the question is
How much more does Colin get over Paul?
Colin------> y
Paul-------> x
y/x=3/2----------> y=x*(3/2)--------> y=1.5x--------> Colin=1.5 Paul
the answer is
Colin did 1.5 times more than Paul