70÷7= 10 yuan

70- 10× 3 = 40 yuan

Original price A = (40- 10) × 7 = 2 10 yuan.

Original price b = (40- 10) × 3 = 90 yuan.

Equation:

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

A = 7× 30 = 2 10 yuan.

B = 3× 30 = 90 yuan