Answer number 20 plz (geometry)

Noor brought 21 sheets of stickers. she gave 1/3 of a sheet to each of the 45 students at recess. she wants to give teachers 1 1/2 sheets each.

The base of a triangle exceeds the height by 7 centimeters. if the area is 400 square centimeters, find the length of the base and the height of the triangle.

Kayla has a $500 budget for the school party.she paid $150 for the decorations.food will cost $5.50 per student. what inequality represents the number of students,s, that can attend the party?