There are several ways to do this. The best way to start is to make the denominators the same. The simplest common multiple to find is 20, since 4 × 5 is 20.
Multiply the numerator and denominator of 1/4 by 5, so it becomes 5/20.
Multiply the numerator and denominator of 4/5 by 4, so it becomes 16/20.
Notice that you didn't have to change the whole numbers.
Now subtract 2 5/20
(which was previously 2 1/4) from both sides of the equation.
On the left side you're left with just m.
On the right side you have 8 16/20 - 2 5/20.
You can subtract just the fractions first, 16/20 - 11/20, so you get 11/20. Subtracting the whole numbers, 8 - 2, gives you 6.
You then have
m = 6 11/20
