Question 119594
multiplying by ab gives a(a+4)=a(a-4)+b(b+4)


subtracting a(a-4) gives a(a+4)-a(a-4)=b(b+4) __ a((a+4-(a-4))=b(b+4) __ a(8)=b(b+4)


dividing by 8 gives a=(b^2+4b)/8