#1. x = - (2y) / (1-y)
#2. x = (-4y-3)/(1-y)
I can't really see the other questions, so I only did the first two. Hope this helps!
Subtraction: 18 - b
Addition: 18 + b
Multiplication: 18b, or 18 x b
Division: 18 divided (My keyboard doesn't have a division sign?) by b
Hope this helped.