Im having issues figuring out if ds/dr = ds/dt = dr/dtbecause they got -0.5/8pir when they declared dr/dt = dS/dt. How and why is this possible?

100%+[}j9 11) A showball melts so that its surface area decreases at a rate of 0.5 cm2 /min. Find the rate at which the radius decreases when the radius is 4 cm. I The formula for Surface Area of a sphere with radius r is 5:4an