Answer:64mi/hour
Step-by-step explanation:
V=speed × time
V=s×t .....equation (1)
v=576
for taking one hour: t-1
speed is: s+8
From equation(1)
V=(s+8)(t-1)
(s+8)(t-1)=576
Expand the bracket
st-s+8t-8=576
Substitute the value of st which is 576
576-s+8t-8=576
Collect the like terms
-s+8t-8=0
s=8t-8
Subtitude into the value of s
576= (8t-8)×t
576=8t^2-8t
8t^2-8t=576
8t^2-8t-576=0 (divide both by 8)
t^2-t-72=0
By factorization method
Product is (-9 and 8)
(t-9)(t+8)=0
t=9 or t=-8
V=s×t
576=s×9
9s=576
s=576/9
s=64mi/hour
