The second time, 240 yuan can get a 15% discount on the original price of a dress: 240*85%=204 yuan.
Two purchases of * * * flowers: 144+204=348 yuan.
She bought these two clothes at one time. The original price is: 160+240=400 yuan, and she can get a 20% discount: 400*80%=320 yuan.
348-320=28 yuan
She used 28 yuan less when she bought these two clothes once than twice.
2. Need for house payment: 30 * 95% = 285,000 yuan.
Pay 1% house deed tax: 28.5 *1%= 2850 yuan = 2850 yuan.
Pay deed tax of 2850 yuan.