The equation of a line in slope-intercept form, is:
Where m represents the slope of the line (rate of change), and b represents the y-intercept of the line (initial value).
Since the rose grows 1.5 cm per day, then the rate of change is 1.5:
Since today the rose is 5cm high, then the initial value is 5:
Then, the height of the rose after x days is:
To find the height of the rose after 20 days, substitute x=20:
Then, the height of the rose after 20 days is 35 cm.