lets write a linear equation to represent this flower growth, lets call y the height of the flower in centimeters and x the number of days passed:
y = 205 + 2x
that means that the flower height y, will grow 2 centimeterrs each x days.
So if we have 235 cm height, we can find the amount of days needed if we replace in the equation and solve for x:
y = 205 + 2x
235 = 205 + 2x
2x = 235 - 205
2x = 30
x = 15
therefore the flower needs 15 days to reach 235 cm height