The living room of Mr. Wang's house is going to be paved with floor tiles. Square floor tiles with a side length of 15 cm will cost 2,000 yuan. If you use square floor tiles with a side length of 25 cm instead, how many pieces are needed? If floor tiles with a side length of 15 cm cost 1.30 yuan each, and floor tiles with a side length of 25 cm cost 3.50 yuan each, which floor tile do you recommend Mr. Wang use? Why?
王老师家的客厅准备铺地砖，用边长15厘米的正方形地砖，需要2000块．如果改用边长25厘米的正方形地砖，需要多少块？如果边长15厘米的地砖每块1.30元，边长25厘米的地砖每块3.50元，你想推荐王老师用哪一种地砖？为什么？
<result>25</result>