General solution:
Number of tables sold in shop A = x
Number of chairs sold in shop A = y
Number of tables sold in shop B = (x - 20)
Number of chairs sold in shop A is 70% of number of chairs sold in shop B
Number of chairs sold in shop B = y/(70) × 100 = (10y/7)
Number of tables sold in shop C = (x - 40)
Number of tables sold in shop D = (60/100) × x = 0.6x
Number of chairs sold in shop C = 80/100 × (10y/7) = 8y/7
Number of chairs sold in shop D = (8y/7) × (75/100) = 6y/7
Total tables sold in all the shops is 170 more than total chairs sold in all the shops
[x + (x - 20) + (x - 40) + 0.6x] - [y + 10y/7 + (8y/7)y + (6y/7)] = 170
(3.6x - 60) - (y + 24y/7) = 170
(3.6x - 60) - (7y + 24y)/7 = 170
25.2x - 420 - (7y + 24y) = 1190
25.2x - 31y = 1610 —----> 1
2 × 31→ x + y = 220 —----->2
25.2x - 31y = 1610
31x + 31y = 6820
56.2x = 8430
x = 150
y = 70
Number of tables sold in shop A = x = 150
Number of chairs sold in shop A = y = 70
Number of tables sold in shop B = (x - 20) = (150 - 20) = 130
Number of chairs sold in shop A is 70% of number of chairs sold in shop B
Number of chairs sold in shop B = y/(70) × 100 = (10y/7) = 10 × 70/7 = 100
Number of tables sold in shop C = (x - 40) = (150 - 40) = 110
Number of tables sold in shop D = (60/100) × x = 0.6x = 150 × (0.6) = 90
Number of chairs sold in shop C = 80/100 × (10y/7) = 8y/7 = 8 × (70/7) = 80
Number of chairs sold in shop D = (8y/7) × (75/100) = 6y/7 = 6 × (70/7) = 60
Solution:
Number of tables sold in shop A = 150
Number of tables sold in shop B = 130
Number of tables sold in the shop E = (150 + 130)/2 = 280/2 = 140 + 25 = 165
Number of chairs sold in shop A = 70
Number of chairs sold in shop D = 60
Number of chairs sold in shop E = (60 + 70)/2 = 130/2 = 65 + 35 = 100
Required total = (165 + 100) = 265