This is hard question can any wan help me

8.2secs

Step-by-step explanation:

Given the expression for calculating the height as;

h = -16x^2+127x+80

Given h = 40

Substitute

40 = -16x^2+127x+80

-16x^2+127x+80 - 40 = 0

-16x^2+127x+40 = 0

16x^2-127x-40 = 0

Factorize

x = -(-127)±√(-127)²-4(16)(-40)/2(16)

x = 127±√16,129+2,560/32

x = 127±√18,689/32

x = 127±136.71/32

x = 127+136.71/32

x = 263.71/32

x = 8.24

Hence the required time to the nearest tenth is 8.2secs