Question

Jenny, who rides a moped, takes 2 hours less to travel 60 miles than Maureen takes to travel 50 miles on her bicycle. Jenny travels 10 miles per hour faster than Maureen. (Hint: speed=distance/time)
Jenny's speed is ______ miles per hour.
Maureen's speed is _____ miles per hour.

Answer 1

Make chart (rate=speed)
distance=time times rate
D=TR
T=D/R
R=D/T
       D          T        R
J      60      x-2         y+10
M      50       x          y

xy=50
(x-2)(y+10)=60
solve for x and y
xy=50
divde both sides by x
y=50/x
subsitute
(x-2)(50/x+10)=60
distribute
50x/x-100/x+10x-20=60
50-100/x+10x-20=60
add like terms
10x-100/x+30=60
10x^2/x-100/x+30=60
(10x^2-100)/x+30=60
subtract 60 from both sides
(10x^2-100)/x-30=0
add 30 to both sides
(10x^2-100)/x=30
multiply both sides by x

10x^2-100=30x
subtract 30x from both sides
10x^2-30x-100=0
factor out the 10
(10)(x^2-3x-10)=0
if you have xy=0 then x and/or y=0 so
10≠0 so (x^2-3x-10)=0
factor by finding what 2 numbers multiply to get -10 and add to get -3
the numbers are -5 and 2 so
(x^2-3x-10)=(x-5)(x+2)=0
so x-5=0
x+2=0

x-5=0
add 5 to both sides
x=5

x+2=0
subtract 2 from both sides
x=-2
false since time cannot be negative

x=5
x times y=50
x=5
5 times y=50
divid eby 5
y=10=Maureen's speed
y+10=10+10=20=Jenny's speed



Jenny's speed is 20 miles per hour
Maureen's speed is 10 miles per hour