Question

Un baiat are intalnire cu o fata la ora 20.00 . Aflati la ce ora porneste el spre locul de intalnire , stiind ca daca ar merge cu 15 km /h ar intarzia 10 minute iar daca ar merge cu 7 km/h atunci ar ajunge cu 20 de minute mai devreme.

Answer 1

$t+ \frac{1}{6}= \frac{d}{5}$
$t- \frac{1}{3}= \frac{d}{7}$

$5(t+ \frac{1}{6})=d$
$7(t- \frac{1}{3})=d$

$7t- \frac{7}{3}=5t+ \frac{5}{6}$

$\frac{42t}6}- \frac{14}{6}= \frac{30t}{6}+ \frac{5}{6}$

42t-14=30t+5
42t-30t=5+14
12t=19
t=19/12 ore

1/12 ore reprezinta 5 minute

19*5=95 minute sau 1ora si 35 minute
20.00-1.35=18.25