This is a standard 2-Step equation.
Step 1 - Isolate the Variable: Add #color(red)(5.1)# to each side of the equation to isolate the #m# term while keeping the equation balanced:
#14.4m - 5.1 + color(red)(5.1) = 2.1 + color(red)(5.1)#
#14.4m - 0 = 7.2#
#14.4m = 7.2#
Step 2 - Solve for the Variable by Multiplying or Dividing by the Appropriate Value: Divid each side of the equation by #color(red)(14.4)# to solve for #m# while keeping the equation balanced:
#(14.4m)/color(red)(14.4) = 7.2/color(red)(14.4)#
#(color(red)(cancel(color(black)(14.4)))m)/cancel(color(red)(14.4)) = 7.2/color(red)(7.2 xx 2)#
#m = color(red)(cancel(color(black)(7.2)))/(color(red)(color(black)cancel(color(red)(7.2))) xx 2)#
#m = 1/2#
Check the Solution: To check the solution substitute #1/2# for #m# and ensure the left side evaluates to the #2.1#
#14.4m - 5.1 = 2.1# becomes:
#(14.4 xx 1/2) - 5.1 = 2.1#
#7.2 - 5.1 = 2.1#
#2.1 = 2.1#