the total cost is divided in the ration 2:3
we can take it as Adam pays 2 parts and Adams dad pays 3 parts
the amount that Adams dad pays is 52.50
Adams dad pays 3 parts thats equivalent to - 52.50
then one part is - 52.50 / 3 = 17.50
the total cost is divided in the 2:3 ratio therefore total cost is equivalent to 2+3 = 5 parts
one part is equivalent to 17.50
therefore 5 parts are equivalent to - 17.50 x 5 = 87.50
the total cost of the meal is 87.50