A set of binary linear equations or inequalities in mathematical problems

1. Let the traffic flow of the Third Ring Road X and the traffic flow of the Fourth Ring Road Y. So B: Y-X=2000, C: 3X-Y= 10000*2=20000, and substitute c: 3 * x-according to b: y = 2000+x.

2. Set public library X at 1978, and the public library in 2008 will be (2X+350). Let the number of museums in 1978 be y, then the number of museums in 2008 is (5Y). According to the meaning of the question, X+Y = 1550, (2x+350)+(5y) = 4650, so 2 * (x+y)+350+3y = 46550. 3y = 4650-3100-350 =1200, so Y = 400, x =1550-400 =150, so the public in 2008