First, multiply each side of the equation by #color(red)(8)# to eliminate the fraction while keeping the equation balanced:
#color(red)(8) xx (5r + 1)/8 = color(red)(8) xx -3#
#cancel(color(red)(8)) xx (5r + 1)/color(red)(cancel(color(black)(8))) = -24#
#5r + 1 = -24#
Next, subtract #color(red)(1)# from each side of the equation to isolate the #r# term while keeping the equation balanced:
#5r + 1 - color(red)(1) = -24 - color(red)(1)#
#5r + 0 = -25#
#5r = -25#
Now, divide each side of the equation by #color(red)(5)# to solve for #r# while keeping the equation balanced:
#(5r)/color(red)(5) = -25/color(red)(5)#
#(color(red)(cancel(color(black)(5)))r)/cancel(color(red)(5)) = -5#
#r = -5#