arithmetic question:

Question

Jenny and Mark share some money in
the ratio two to three. Jenny’s share
is one hundred and ten pounds.
How much is Mark’s share?

Answer 1

Ratio means a fraction.  This problem states that
    (Jenny’s share) / (Mark’s share)   =   2/3      ( or  J:M  is 2:3)
 And
        110 £ / (Mark's share) = 2/3

We can invert both fractions:
           M / 110  =  3/2
           Mark’s share = 165 £