Answer:
13.615
Step-by-step explanation:
d = 19 mi
Total dist = bike dist + train dist
d = 12(.5) + 20(.5)
d = 6 + 13
3x(x²-5)
Multiply the bracket by 3x
(3x)(x^2)=3x^3
(3x)(-5)=15x
Answer: 3x^3+15x