Please help!! ill give brainliest!!! this is worth 30 points!!!!!!!!

Answer: a. 45 = k
b. d/t = 45
c. d = 45t
Step-by-step explanation:
The constant of proportionality (k) equals y divided by x if it is a direct variation. In the given problem, y is represented by distance (d) and x is represented by time (t).
[tex]a)\quad \dfrac{d}{t}=k\\\\\\.\qquad \dfrac{90}{2}=k\\\\\\.\qquad 45=k\\\\\\b)\quad \dfrac{d}{t}=k\\\\\\.\ \quad \dfrac{d}{t}=45\\\\\\c)\quad \text{multiply both sides by t:}\\.\qquad d=45t[/tex]