Hello Isle,
The formula for the equation of a line is: y = mx + b; m is the slope and b is the y-intercept.
You're given both: you're told the slope is 3 so m = 3, and the y-intercept is 4.5 so b = 4.5
Therefore, the equation of the line is: y = 3x + 4.5
Isle E.
thank you!01/26/22