(1/2x + 3/4 = 9 ( original equation)
1/2x +3/4 - 3/4 = 9 - 3/4 ( subtracting 3/4 from the left so that way the numbers can be on one side)
1/2x = 8 1/4 or 33/4 ( after subtracting 3/4 from 9)
4x = 66 ( this is cross multiplying, you multiply 1x4 and 2 x33)
x = 66/4, x = 33/2
x = 16 1/2