Solve the equation a = m – n for the variable n

a=m-n

(Add n to both sides)

a+n=m-n+n

(The -n and +n cancel out, on the right side of the equation)

a+n=m

(Now subtract a from both sides)

a+n-a=m+a

(The +a and -a cancel out, on the right side of the equation)

n=m+a

Step-by-step explanation:

Adding to both sides.

Subtracting from both sides.

72 is the answer to this problem