Write the fraction as a sum of unit fractions 3/10

Itook a better photo of the question so y’all can see it i hope it’s a fine photo

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.

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)