Question 121073
Is the correct answer 6?I THINK THAT 6 IS HER RATE ON THE FREEWAY????


Distance(d) equals Rate(r) times Time(t) or d=rt; r=d/t and t=d/r

Let r=Adriana's rate on the freeway
then r+6=her rate on the side roads

time on the side roads=30/(r+6)
time on the freeway=15/r

and we are told that the above two times are equal, so:

30/(r+6)=15/r  multiply each side by r(r+6) {or cross-multiply}
30r=15(r+6) get rid of parens
30r=15r+90  subtract 15 from both sides
30r-15r=15r-15r+90  collect like terms

15r=90 divide both sides by 15
r=6 mph--------------------------------her rate on the freeway
r+6=6+6=12mph----------------------------her rate on the side roads

CK
30/12=15/6
15/6=15/6

Hope this helps----ptaylor