<span> 10a 10а 2а</span>
<span>--------- = ------------ = -----------</span>
<span>5a+5b 5(а+b) а+b</span>
1) 19 1/4 + 17 5/6 = 19 3/12 + 17 10/12 = 36 13/12 = 37 1/12
2) 37 1/12 • 8,4 = 445/12 • 42/5 = 1869/6 = 623/2 = 311,5
3) 311,5 + 7,5 = 319
Ответ 319