Solution: Let the original price of A be 7X yuan and the original price of B be 3X yuan.
(7X+70):(3X+70)=7:4
28X+280=2 1X+490
7X=2 10
X=30
The original price of A is: 7× 30 = 2 10 (yuan).
B Original price: 3× 30 = 90 yuan.