有關 Introduction to Algebra

1. Simplify the following algebraic expressions.
(a) 3X + X - 2X
=
(b) 5m -5 - 2 (2m+1)
=
(c)
圖片參考：http://us.f6.yahoofs.com/hkblog/nxmf8DaGGRkSUBH9Xooahcnu60OH8mONxw--_1/blog/20080820110917271.jpg.jpg?ib_____DLPx5V6Db

(d)
圖片參考：http://us.f6.yahoofs.com/hkblog/nxmf8DaGGRkSUBH9Xooahcnu60OH8mONxw--_1/blog/20080820110927307.jpg.jpg?ib_____DoaAPj38_


2. By the method of substitution, find the values of the following expressions if X = 2 and y =3.
(a) 7X - 2Y (b)X/4(四分之X) + y/6(六分之Y)
= =
(c)
圖片參考：http://us.f6.yahoofs.com/hkblog/nxmf8DaGGRkSUBH9Xooahcnu60OH8mONxw--_1/blog/20080820111422238.jpg.jpg?ib_____DrJKFL83d

3.Simplify the following algebraic expressions.
(a) 3r +4s -2r +7s
(b)
圖片參考：http://us.f6.yahoofs.com/hkblog/nxmf8DaGGRkSUBH9Xooahcnu60OH8mONxw--_1/blog/20080820111724304.jpg.jpg?ib_____D.BJKMRAU

(c)a +2b+3c+4a+6b-2c
(d) 2xy+3x-2y+4x-6y+5xy

以上。本人至今還未會做的題目。望高手指教。