Question 159779
1/4 of an hour is .25

X=the time traveled by Nikki

X+.25=time traveled by Jack

(speed)(time)=distance

10(X)=distance Nikki traveled
12(X+.25)=distance Jack traveled

The equation is

X(10)+6=12(X+.25)

10X+6=12X+3

Subract 10X from each side

6=2X+3

Subtract 3 from both sides 
3=2X

Divide 2 on both sides

1.5 =X

1.5 is the time it took Nikki to ride

(1.5+.25)=1.75 hour time it took Jack to ride

Plug in values to check your answer

10(1.5) +6=12(1.75)

15+6=21

21=21