Cross Multiply by 'x - 5'
Hence
y(x - 5) = 4 -3x
xy - 5y = 4 - 3x
Move all the terms containing an 'x' to one side of the equals and all the others to the opposite side.
xy + 3x = 4 + 5y
Factor out 'x'
x(y + 3) = 4 + 5y
'Cross' divide by 'y + 3'
x = ( 4 + 5y) / (y + 3 )
'x' is now the subject.
