It takes 6 seconds for it to hit the ground.
0 = -5x²+20x+60
We can solve this by factoring. First factor out the GCF, -5:
0 = -5(x²-4x-12)
Now we want factors of -12 that sum to -4. -6(2) = -12 an -6+2 = -4:
0 = -5(x-6)(x+2)
Using the zero product property, we know that either x-6=0 or x+2=0; this gives us the answers x=6 or x=-2. Since we cannot have negative time, x=6.
-0.4x=2.5 divide both sides by -0.4
x=-6.25
It looks like a 126%angle ok
