“The height of an arrow” NEED HELP WITH THIS QUESTION ASAP!

Answer:a) t = 0.54 secondsb) t = 8 secondsStep-by-step explanation:Given in the question the equationh = 40t - 5t² where h is height in meters             t is time in secondsTime it took to reach 20 meters 20 = 40t - 5t²-5t² + 40t - 20 = 0by using quadratic formula for factorisation t = (-b± √(b)² - 4(a)(c) ) / 2(a)t = 0.54 (upward motion)or t = 7.46 (downward motion)b) Time it took to reach the ground at ground h = 0So,0 = 40t - 5t² t(40 - 5t ) = 0t = 0 (at starting point)or 40 -5t = 0 5t = 40t = 40 /5 t = 8 seconds