On a grid does the x axis or y axis come first?

the formula for the cost is

c = l + p

Total cost is £47

Step-by-step explanation:

Let c represent the cost in £ of a monthly phone contract made up of the fixed line rental l in £ and the price p in £ of the calls made.

The formula for the cost, c would be

c = l + p

if the line rental is £35 and the price of calls made is £12, then, the total cost, c would be

c = 35 + 12 = £47