Question

треба 2,3 1 способом

Answer 1

Пошаговое объяснение:

$2) \: \frac{7}{x + 4} = \frac{21}{60} \\ (x + 4) \times 21 = 7 \times 60 \\ x + 4 = \frac{60 \times 7}{21} \\ x + 4 = \frac{60 \times 1}{3} \\ x + 4 = \frac{20}{1} \\ x = 20 - 4 \\ x = 16$

$3) \: \frac{5x - 8}{5} = \frac{18}{45} \\ 5x - 8 = \frac{18 \times 5}{45} \\ 5x - 8 = \frac{2 \times 5}{5} \\ 5x - 8 = \frac{2 \times 1}{1} \\ 5x = 2 + 8 \\ 5x = 10 \\ x = \frac{10}{5} \\ x = 2$