a/5=b/7
a=5×b/7 (!)
a+5/b+1=a+b/b+10
(5×b/7+5)/b+1=(5×b/7+b)/b+10. (am inlocuit a cu (!) )
5b+35/7b+7=5b+7b/7b+70
(5b+35)(7b+70)=(5b+7b)(7b+7)
(5b+35)(b+10)=12b(b+1)
o sa notez cu B=b la patrat
5B+35b+50b+350=12B+12b
7B-73b-350=0
ecuatia de gradul 2
D=73×73-4×7×(-350)
D=5329+9800
D=15129=123 la patrat
b1=(73+123)/14=14 rezulta din(!) ca a1=10
b2=(73-123)/14=-50/14=-25/7 rezulta din (!) ca a2=-125/49
