I need the area of ABC but don't know how to get the base.

Base=Width x Length

if you are finding this for a triangle, then it is 1/2 Width x Length

From my viewpoint; your length is 4 and your width is 5, so your base should be 20 units

(sorry if this isn't complete; I was having some trouble understanding the full question)

the graph in the attached figure

step-by-step explanation:

we have

using a graphing tool

the graph in the attached figure

the roots are ( x-intercepts) x=-0.5,x=1,x=3

the y-intercept is the point (0,3)