Answer:
n = m − a
Step-by-step explanation:
Given:
a = m - n
Where,
a = Actual cost an item
m = Original price
n = amount of coupon
Solve the formula for the amount of the coupon
a = m - n
Add n to both sides
a + n = m - n + n
a + n = m
Subtract a from both sides
a + n - a = m - a
n = m - a
Amount of coupon, n = Original price of an item, m - Actual cost of an item, a