Question 1121392
a. x=18
0.4(324)-576+820=129.6-576+820=373.6 accidents/50 M miles

b. 0.4(2500)-1600+820=220 accidents/50 M miles 

c. The x value for the vertex is -b/2a=32/0.8 or 40 years old (180 accidents/50 M miles)