Question

помогите пожалуйста!
​

Answer 1

а)  $\dfrac{2,4}{16,8} = \dfrac{24}{168} = \boxed{\bf{\dfrac{1}{7}}}$

б)  $\dfrac{1\dfrac{2}{5}}{2\dfrac{4}{15}} = \dfrac{7}{5} : \dfrac{34}{15} = \dfrac{7\cdot 15}{5\cdot 34} = \dfrac{7\cdot 3}{34} = \boxed{\bf{\dfrac{21}{34}}}$

в)  $\left(1\dfrac{2}{3} + 2\dfrac{4}{9}\right) : \left(4\dfrac{26}{27} - 2\dfrac{2}{9}\right) = 1,5$

          1)  $1\dfrac{2}{3} + 2\dfrac{4}{9} = 1\dfrac{6}{9} + 2\dfrac{4}{9} = 4\dfrac{1}{9}$

         2)  $4\dfrac{26}{27} - 2\dfrac{2}{9} = 4\dfrac{26}{27} - 2\dfrac{6}{27} = 2\dfrac{20}{27}$

        3)  $4\dfrac{1}{9} : 2\dfrac{20}{27} = \dfrac{37}{9}: \dfrac{74}{27} = \dfrac{37\cdot 27}{9\cdot 74} = \dfrac{3}{2} = \boxed{\bf{1,5}}$

2.

$x - \dfrac{8}{11}x = 4,8\\\\\\\dfrac{11}{11}x - \dfrac{8}{11}x = 4,8\\\\\\\dfrac{11-8}{11}x = 4,8\\\\\\\dfrac{3}{11}x = 4,8\\\\\\x = 4,8 : \dfrac{3}{11}\\\\\\x = \dfrac{48}{10} : \dfrac{3}{11}\\\\\\x = \dfrac{48\cdot 11}{10\cdot 3}\\\\\\x = \dfrac{16\cdot 11}{10}\\\\\\x = \dfrac{176}{10}\\\\\boxed{\bf{x = 17,6}}$

Ответ: 17,6.

3.  $420 : \dfrac{6}{7} = \dfrac{420\cdot 7}{6} = 70\cdot 7 = \boxed{\bf{490}}$ га.

Ответ: 490 га.

4.

    1) 100 - 24 = 76% - составляют 38 км.

38 км - 76%

x км - 100%

$x = \dfrac{38\cdot 100}{76} = \dfrac{100}{2} = \boxed{\bf{50}}$  км.

Ответ: 50 км.

5.

    1) 2,94 : 0,7 = 4,2 - 40% числа х.

4,2 - 40%

х - 100%

$x = \dfrac{4,2\cdot 100}{40} = \dfrac{420}{40} = \dfrac{42}{4} =\dfrac{21}{2} = \boxed{\bf{10,5}}$

Ответ: 10,5.