Question

Помогите с математикой ! 12 Задание Огэ

Answer 1

$40 = \frac{t1 - 300}{t1} \times 100$

$\frac{4}{10} = \frac{t1 - 300 }{t1}$

$4t1 = 10(t1 - 300)$

$- 6t1 = - 3000$

$t1 = 500$