I've got some exercises which I want to solve:

http://images50.fotosik.pl/143/c0d712777e4a103d.jpg

First of all I tried to solve 5th, which is about operational amplifiers:

http://images50.fotosik.pl/143/6fdddbfe3bb4f2d3.jpg

but I've got difficulty with transforming formula. Can anybody help me?

Thanks in advance

Greetings!