What are two equivalent fractions for 11/13?
As long as the top and bottom of the fraction are kept to the same ratio - so the top and bottom numbers change by the same multiplier - the fraction is still the same.
We are not given specifics so we can choose what we wish.
Both 11 and 13 are prime numbers so we can not reduce them proportionately and still have whole numbers. Thus we will need to increase them.
Multiply by 1 and you do not change the actual value. However, 1 comes in many forms.