8. Lei Lei bought some goats and sheep. If she bought 2 more goats, the average price per sheep would increase by 60 yuan. If she bought 2 fewer goats, the average price per sheep would decrease by 90 yuan. Lei Lei bought $\qquad$ sheep in total.
【Answer】Solution: Assume Leilei bought $x$ sheep, the original average price was $a$ yuan. Buying 2 goats would increase the average price of each sheep by 60 yuan, and the total price would increase by $60 x+2 (a+60)$ yuan;

If 2 fewer goats were bought, then the average price of each sheep would decrease by 90 yuan, and the total price would decrease by $90 x+2 (a-90)$ yuan. Both changes are due to the price of two goats, so they should be equal,

Therefore, $60 x+2(a+60)=90 x+2(a-90)$, solving this gives $x=10$, so the answer is 10.