Answer is £87
Both Adam and his dad payed for a meal, so you need to find out how much each of them payed individually, then add up how much they payed for the total cost.
Adam's dad pays £52.20 from the ratio of Adam:Dad to 2:3.
You need to find the cost of 1/5 of the meal to work out the total cost using the ratios (since 2+3=5).
So divide £52.20 by 3 (using the ratios) in order to find the cost of 1/5 of the cost of the meal.
52.20 / 3 = £17.40 (cost of 1/5 of the cost of the meal)
Using the ratios, first find out how much Adam payed.
£17.40 x 2 = £34.8
You do not need to work out how much Adam's dad payed since the cost is already given in the Q, however you can check to see if your answer gives the cost that is given in the question.
£17.40 x 3 = £52.20
Afterwards, add up the amount that Adam and his dad payed.
£34.80 + £52.20 = £87
Hope this helped :)