Tow-Thomas biquad filter design
It makes up for easier analysis, I'm not going to analyze this for you because it's a homework question, I'll show you a different example so I don't deprive you of valuable learning. I you look at an instrumentation amplifier equation it helps to have resistors equal each other for the overall gain (and common mode). 


$$\frac{V_{out}}{\Delta V_{in}}  = \bigg(1+\frac{2R_2}{R_1}\bigg)\bigg(\frac{R_6 (R_3+R_4)}{R_3 (R_5+R_6)}+\frac{R_4}{R_3}\bigg)$$

If we let R3=R5 and R4=R6 you get this:

$$\frac{V_{out}}{\Delta V_{in}}  = 2\frac{R_4}{R_5} $$

So the answer is in a round about way is it makes things nice for analysis and circuit design.

To solve this find the transfer function of each block and solve it open loop (by treating the first stage as an summing amplifier and breaking the loop between R3 and R4). Then set the output of the first stage equal to the other disconnected input of the summing amplifier