设每台进价是x元,则每台的卖价是(1+5℅)x元,按标价5250元的8折出售的卖价是0.8×5250元,根据题意,有方程：
(1+5℅)x=0.8×5250
1.05x=4200
x=4000
答：每台彩电的进价是4000元.