Question

пожалуйста прошу быстрее, и правильно​

Answer 1

Смотри во вложении)

Answer 2

Пошаговое объяснение:

1)

$\frac{1}{2} a + \frac{1}{3} a - \frac{1}{4} a = \frac{6}{12} a + \frac{4}{12}a - \frac{3}{12}a = \frac{7}{12} \times 1 \times \frac{5}{7} = \frac{7}{12} \times \frac{12}{7} = 1$

2)

$\frac{4}{7} b + \frac{5}{21} b - \frac{2}{3} b = \frac{12}{21} b + \frac{5}{21}b - \frac{14}{21}b = \frac{1}{7} b = \frac{1}{7} \times 2 \times \frac{1}{3} = \frac{1}{7} \times \frac{7}{3} = \frac{1}{3}$

3)

$1 \times \frac{5}{12} m + 2 \times \frac{7}{18} m - 1 \times \frac{2}{9} m = 1 \times \frac{15}{36}m + 2 \times \frac{14}{36}m - 1 \times \frac{8}{36}m = 2 \times \frac{7}{12} m = 2 \times \frac{7}{12} \times 1 \times \frac{17}{31} = \frac{31}{12} \times \frac{48}{31} = 4$