Answer
8x^3 - 6x^4 + 12x^3
20 minutes = 1/3 of an hour
1/3 = 0.333
1/3 x 45mph = 15, so she drove 15 miles at 45mph
18-15 = 3
3 miles/ 20 mph = 0.15 hours
0.333+0.15 = 0.483 hours total
0.483 x 60 = 28.98 so approximately 29 minutes total driving time
7:15 + 29 minutes is 7:44 am she arrived at work
5(2x-3)+7
distribute the 5 to the 2x and -3
10x-15+ 7
combine like terms -15+7
10x-8
