Linear Equations

Write two different linear equation in two variables.
$$50x + 24y = 1000$$
$$x + y = 100$$
Taylor is $$x$$ years old where as his father's age is $$20$$ years more than twice his present age. After $$5$$ year , Taylor's father will be $$3$$ times as old as Taylor. How old is Taylor?
Simplify $$7x-9y+3-3x-5y+8$$.
Solve the following question using a systematic method
1) 7x=28
2) 2x+7=13
3) -y+36=32
4) 2y-6=8