What is the least possible degree of a polynomial that has roots -5,1+4i, and -4i?

Asap for seven months an ice creams vendor collects data showing the number of cones sold a day (c) and the degrees above 70 degrees f the vendor finds that there is a positive linear association between c and t that is the best modeled by this equation c=3.7t+98 which statement is true? the model predicts that the average number of cones sold in a day is 3.7 the model predicts that the average number of cones sold i a day is 98 a model predicts that for each additional degree that the high temperature is above 70 degres f the total of number of cones sold increases by 3.7 the model predicts for each additional degree that the high temperature is above 70 degrees f the total number of cones sold increasingly by 98

Acredit card advertises an annual interest rate of 23%. what is the equivalent monthly interest rate?

How do you use the elimination method for this question? explain, because i really want to understand!