Help I don't know how to solve this

In the rectangle below ac=30 units what is de

Aschool allots ? 1500 to spend on a trip to the theatre. theatre tickets have a regular cost of ? 55 each and are on offer for 1 5 off. a train ticket for the day will cost ? 12 each. if 2 teachers and the maximum number of students attend, how much money will the school have left over?

When i'm with my factor 5, my prodect is 20 .when i'm with my addend 6' my sum is 10.what number am i