How can you find the answer of 15 only using the numbee 4

During your cycling trip, you and your friends often stayed in hostels. the prices of these are listed below. hostel standard room (price per night) with breakfast (price per night) super sleep hostels £22.45 £28.65 normandy nights £18.55 £25 zzzola hostels £24.50 £30.99 belgian beds £11.20 £18.55 night-time rest days ? £33 what is the range in cost for a single night, including both standard room prices and with breakfast prices?

Does anyone know how to do geometryme with this problem

The roots of the function f(x) = x2 – 2x – 3 are shown. what is the missing number?