## anonymous 4 years ago 9. Lisa can ride her bike to work in 2/3 of an hour. When she drives to work it takes 1/3 of an hour. If she drives 12 miles per hour faster than she rides her bike, how fast does she ride her bike? 12 mph 6 mph 15 mph 18 mph

1. anonymous

let $v_c=v+12$ $v_b=v$

2. anonymous

let v be her "normal" velocity and s be the distance to work s = v * (2/3) s = (v+12) * (1/3) divide the equations and get (v+12) = 2v v = 12

3. anonymous

if $V=\frac{d}{t}$ $v*t=d$

4. anonymous

thanksssss

5. anonymous

since distances are the same $v*\frac{2}{3}=(v+12)\frac{1}{3}$ $\frac{2}{3}v=\frac{1}{3}v+4$ $\frac{1}{3}v=4$ $v=12$