(х+2)+х=9 9-2=7 7-2=5 (5+2)+2=9
6 1/2=3 8/15+7/12+x
x=6 1/2 - 3 8/15 - 7/12
x = 13/2 - 53/15 - 7/12
x = 390/60 - 212/60 - 35/60
x = 143/60 = 2 23/60
Крест на крест - пропорция :
<span>24=7
<span>
48=х
</span></span>
<span>х=7*48 /24=14
Ответ : 14
</span>