Answer:
5 cm/s
Step-by-step explanation:
The rate of change (ROC) is the speed at which the y variable (hieght) increases with the x variable (time). so ROC = 5.
the linear equation is y = mx + b, m is also the roc, b is the initial value, so,
if y = 60, x = 4 & b = 40, then making m the subject of equation will give the value of the ROC. i.e m = (y - b)/x = (60 - 40)/4.
