Multiply each side of the equation by #color(red)(-0.5)# to solve for #y# while keeping the equation balanced:

#color(red)(-0.5) xx -0.12 = color(red)(-0.5) xx y/-0.5#

#0.06 = cancel(color(red)(-0.5)) xx y/color(red)(cancel(color(black)(-0.5)))#

#0.06 = y#

#y = 0.06#

To check the solution we need to substitute #0.06# for #y# back in the original equation and calculate the left side of the equation. If the left and right side of the equation are then equal, the solution is validated:

#-0.12 = y/-0.5# becomes:

#-0.12 = 0.06/-0.5#

#-0.12 = -0.12#