Point E is the centroid of triangle ABC. Find DB.

AF = 10x=3
EF = 2x+5
EB = 4x+3

This is for median of triangles.

2 answers

You have probably learned that the centroid divides a median in the ratio of 2:1, with the longer side towards the vertex.

I will assume that the median is AF, and you meant
AF = 10x + 3

so AF : EF = 2:1
(10x+3)/(2x+5) = 2/1
crossmultiply
10x + 3 = 4x + 10
6x = 7
x = 7/6

Not enough information to find DB.
Was the triangle isosceles or equilateral?
Triangle is isosceles.