Question

Отдам 40 баллов за решение

Answer 1

3/20*15+7/30*15=45/20+105/30=1350/600+2100/600=3450/600=5.75

Answer 2

$( \frac{3}{20} + \frac{7}{30} ) * 15 = \frac{3*3 + 7*2}{60} * \frac{15}{1} = \frac{9+14}{60} * \frac{15}{1} = \frac{23 * 15}{60*1} = \\ \\ = \frac{23 *1}{4*1} = \frac{23}{4} = 5\frac{3}{4} = 5,75$

Ответ: 5,75.