Ответ:
Пошаговое объяснение:
1) 80 км/ч - 62 км/ч = 18 км/ч скорость догона
2) 72 : 18 = 4 часа
1дм=10см
![l=6cm+10cm+3cm=19cm](https://tex.z-dn.net/?f=l%3D6cm%2B10cm%2B3cm%3D19cm)
Кстати,
![l](https://tex.z-dn.net/?f=l)
-
это длина.
Вот и всё.
Желаю пятерок!!!
Ответ неправильный, модераторы всё равно его удалят...
А)
![\frac{1}{6} + \frac{1}{9} = \frac{3+2}{18}= \frac{5}{18}](https://tex.z-dn.net/?f=+%5Cfrac%7B1%7D%7B6%7D+%2B++%5Cfrac%7B1%7D%7B9%7D+%3D++%5Cfrac%7B3%2B2%7D%7B18%7D%3D++%5Cfrac%7B5%7D%7B18%7D++)
б)
![\frac{2}{9} + \frac{5}{6} = \frac{4+15}{18} = \frac{19}{18} = 1 \frac{1}{18}](https://tex.z-dn.net/?f=+%5Cfrac%7B2%7D%7B9%7D+%2B++%5Cfrac%7B5%7D%7B6%7D+%3D++%5Cfrac%7B4%2B15%7D%7B18%7D+%3D++%5Cfrac%7B19%7D%7B18%7D+%3D+1+%5Cfrac%7B1%7D%7B18%7D+++)
в)
![\frac{2}{9} + \frac{3}{8} = \frac{16+27}{72}= \frac{43}{72}](https://tex.z-dn.net/?f=+%5Cfrac%7B2%7D%7B9%7D+%2B++%5Cfrac%7B3%7D%7B8%7D+%3D++%5Cfrac%7B16%2B27%7D%7B72%7D%3D+%5Cfrac%7B43%7D%7B72%7D++)
г)
![\frac{2}{10} + \frac{6}{15} = \frac{1}{5} + \frac{2}{5} = \frac{3}{5}](https://tex.z-dn.net/?f=+%5Cfrac%7B2%7D%7B10%7D+%2B++%5Cfrac%7B6%7D%7B15%7D+%3D++%5Cfrac%7B1%7D%7B5%7D+%2B++%5Cfrac%7B2%7D%7B5%7D+%3D++%5Cfrac%7B3%7D%7B5%7D+)
— сократили обе дроби (первую на два, вторую на три)
д)
![\frac{3}{10} + \frac{2}{12} = \frac{3}{10} + \frac{1}{6} = \frac{9+5}{30} = \frac{14}{30} = \frac{7}{15}](https://tex.z-dn.net/?f=+%5Cfrac%7B3%7D%7B10%7D+%2B++%5Cfrac%7B2%7D%7B12%7D+%3D++%5Cfrac%7B3%7D%7B10%7D+%2B++%5Cfrac%7B1%7D%7B6%7D+%3D++%5Cfrac%7B9%2B5%7D%7B30%7D+%3D++%5Cfrac%7B14%7D%7B30%7D+%3D++%5Cfrac%7B7%7D%7B15%7D++)
е)
![\frac{5}{12} + \frac{4}{15} = \frac{25+16}{60} = \frac{41}{60}](https://tex.z-dn.net/?f=+%5Cfrac%7B5%7D%7B12%7D+%2B++%5Cfrac%7B4%7D%7B15%7D+%3D++%5Cfrac%7B25%2B16%7D%7B60%7D+%3D++%5Cfrac%7B41%7D%7B60%7D+)
ж)
![\frac{3}{4} + \frac{5}{18} = \frac{21+10}{36} = \frac{31}{36}](https://tex.z-dn.net/?f=+%5Cfrac%7B3%7D%7B4%7D+%2B++%5Cfrac%7B5%7D%7B18%7D+%3D++%5Cfrac%7B21%2B10%7D%7B36%7D+%3D+%5Cfrac%7B31%7D%7B36%7D+)
з)
![\frac{2}{26} + \frac{3}{39} = \frac{1}{13} + \frac{1}{13} = \frac{2}{13}](https://tex.z-dn.net/?f=+%5Cfrac%7B2%7D%7B26%7D+%2B++%5Cfrac%7B3%7D%7B39%7D+%3D++%5Cfrac%7B1%7D%7B13%7D+%2B++%5Cfrac%7B1%7D%7B13%7D+%3D++%5Cfrac%7B2%7D%7B13%7D++)
и)
![\frac{7}{34} + \frac{5}{51} = \frac{42+20}{204} = \frac{62}{204} = \frac{31}{102}](https://tex.z-dn.net/?f=+%5Cfrac%7B7%7D%7B34%7D+%2B++%5Cfrac%7B5%7D%7B51%7D+%3D++%5Cfrac%7B42%2B20%7D%7B204%7D+%3D++%5Cfrac%7B62%7D%7B204%7D+%3D++%5Cfrac%7B31%7D%7B102%7D+)
к)
![\frac{4}{210} + \frac{5}{140} = \frac{8+15}{420} = \frac{23}{420}](https://tex.z-dn.net/?f=+%5Cfrac%7B4%7D%7B210%7D+%2B++%5Cfrac%7B5%7D%7B140%7D+%3D++%5Cfrac%7B8%2B15%7D%7B420%7D+%3D++%5Cfrac%7B23%7D%7B420%7D+)
л)
![\frac{7}{450} + \frac{8}{180} = \frac{14+40}{900} = \frac{54}{900} = \frac{3}{50}](https://tex.z-dn.net/?f=+%5Cfrac%7B7%7D%7B450%7D+%2B++%5Cfrac%7B8%7D%7B180%7D+%3D++%5Cfrac%7B14%2B40%7D%7B900%7D+%3D++%5Cfrac%7B54%7D%7B900%7D+%3D++%5Cfrac%7B3%7D%7B50%7D)
м)
![\frac{9}{180} + \frac{7}{120} = \frac{3}{60} + \frac{7}{120} = \frac{6+7}{120} = \frac{13}{120}](https://tex.z-dn.net/?f=+%5Cfrac%7B9%7D%7B180%7D++%2B++%5Cfrac%7B7%7D%7B120%7D+%3D++%5Cfrac%7B3%7D%7B60%7D+%2B++%5Cfrac%7B7%7D%7B120%7D+%3D++%5Cfrac%7B6%2B7%7D%7B120%7D+%3D++%5Cfrac%7B13%7D%7B120%7D+)