The slope-intercept form of a line is y = mx + b, where m is the slope and b is the y-intercept. Since you are given the slope (0.5) and the y-intercept (3), all you have to do is substitute these given values into the equation. Substituting them in you get: y = 0.5x + 3, which is your answer.
You can draw the 3 rectangles with these measurements then divide one horizontally one vertically and one slanted from one top corner to one bottom corner