Christy drove 300 miles on her vacation. She drove 1.25 time faster on the second 150 miles of her trip than on the first. Which expression represents the time she spent driving? Let x be her speed for the fist half.

Question

Christy drove 300 miles on her vacation. She drove 1.25 time faster on the second 150 miles of her trip than on the first. Which expression represents the time she spent driving? Let x be her speed for the fist half. 
A. 375/x**
B.337.5/x
C.270x
D.270/x
Simplify x/6x-x^2
A. 1/6-x where x does not = 0x6
B. 1/6-x where x does not = 6
C. 1/6x where x does not = 0
D. 1/6**
Simplify 5x^3/7x^3+x^4
5/7+x; where x is not equal to 0, -7**
5/7+x; where x is not equal to -7
5/7x; where x is not equal to 0
5/7

Reiny · Answer

#1
speed on first leg ---- x mph
speed on 2nd leg --- 1.25x mph
150/x + 150/1.25x
= 150/x + 120/x
= 270/x

#2, you must have meant:
x/(6x-x^2)
= x/(x(6 - x))
= 1/(6-x), x ≠ 0,6

#3 again watch you brackets
5x^3/7x^3+x^4
= 5x^3/(x^3(7 + x)
= 5/(7+x) , x ≠ 0,-7