(1) 500 * 0.8+100 * 0.7 = 470 yuan.

(2) If the original purchase price is above 500 yuan, it should be above 400 yuan.

If 320 yuan and 750 yuan are paid separately, 320 yuan is a project within 500 yuan and 750 yuan is a project outside 500 yuan.

320 divided by 0.8=400 yuan, and 400 yuan in 750 yuan is 500 after 20% discount, so 350 divided by 0.7=500 yuan, so the original price of goods bought twice is 400+(500+500)= 1400 yuan, and if bought twice together, it is 500*0.8=400 yuan, (.