<span>x*3-25=245
3х-25=245
3х=245+25
3х=270
х=90</span>
X-5 7/39=8 3/24
X-5 168/936=8 117/936
X=5 168/936+8 117/936
X=13 285/936
Ответ:13 285/936
1,25/(-2/5)=6,25/-2= -3,125=- 25/8
1,75/(1 целая 1/8)=(7/4)/(9/8)=14/9
-25/8 +14/9= (112-225)/(8*9)= -113/(8*9)
-113/2*8*9= -113/144