Х+3/х-7 - 10/х+7 = 140/ х²-49
(X+3)/(X-7)-10/(X+7)=140/(X^2-49)
(X+3)/(X-7)-10/(X+7)=140/(X+7)(X-7)
(X+3)^2-10(X-7)=140
X^2+6X+9-10X+70-140=0
X^2-4X-61=0