Question 1078135
rate(r) * time (t) = distance
:
1)  r * t = 30
2)  (r+10) * (t-0.1) = 30
:
By equation 1, t = 30/r
:
(r + 10) * (30/r-0.1) = 30
:
(r + 10) * (30-0.1r)/r = 30
:
(r+10) * (30-0.1r) = 30r
:
0.1r^2 +r -300 = 0
:
r^2 +10 -3000 = 0
:
(r+60) *(r-50) = 0
:
r = -60 or 50, we reject the negative rate
:
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Jacqui's new speed is 50 + 10 = 60 mph
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