You and 4 friends plan a surprise party. each of you contributed the same amount of money m for food.

m denotes how much money each person contributes.

Let n be the number of friends.

Let 1 denote including yourself

Let T denote the total amount of money.

T = m (n+1)

If you have 4 friends,

T = m (4+1)

T = ($5.25) (5)

T = $26.25

Then they've spent $26.25 altogether (Includes yourself contributing)