Answer:
90 miles!
Step-by-step explanation:
there are two parts to the problem, meaning you'll need 2 equations.
let's call the distance TO the grandma's house d1, and BACK from the grandma's house d2.
KEY:
time TO g'ma house= t1
time FROM g'ma house=t2
(replace the t's with 's' for speed, with the '1' for to, and '2' for from)
(distance is a constant so d1 is always equal to d2).
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d1=s1+t1, d2=s2+t2
we know what t1 is. 2 hours.
d1=s1•2
meaning that d2 is also equal to that.
s1•2=(s1-5)•2 1/4
2s1=2 1/4 s1-11 1/4
11 1/4= 2 1/4 s1-2s1
11 1/4 = 1/4 s1
s1 (to g'ma)=45 mph
distance is speed times time.
so 45•2 (hr) = 90.
