6≥X-5

X≤ 1 1

Third, 1,

9A+ 10B= 18 10.............①

12A+8B= 1880..............②

Get A=(470-2B)/3...........③ from ②.

Substitution into ① gives 3 (470-2b)+10b =1810.

14 10-6B+ 10B = 18 10

4B = 18 10- 14 10 = 400

B= 100

By ③ formula A = (470-2×100)/3 = 270/3 = 90.