Two friends, Alejandra and Mia, agreed to split the check at a restaurant. Alejandra ordered $12 worth of food and Mia ordered $18 worth. At the end of the meal, Alejandra put her $12 contribution on the table, plus a 20% tip and Mia put her $18 contribution on the table, plus a 15% tip.

The total tip left by Alejandra and Mia is equal to r\% of the total check for their table, where the "total check" amount does not include the tip. What is r?

Question

Two friends, Alejandra and Mia, agreed to split the check at a restaurant. Alejandra ordered $12 worth of food and Mia ordered $18 worth. At the end of the meal, Alejandra put her $12 contribution on the table, plus a 20% tip and Mia put her $18 contribution on the table, plus a 15% tip.

The total tip left by Alejandra and Mia is equal to r\% of the total check for their table, where the "total check" amount does not include the tip. What is r?

schoolgeek15 · Answer

12 X .20 = 2.4 
18 X .15 = 2.7 
r= 5.1

scott208 · Answer

so its what % of 30 is 5.1

mangotangochick · Answer

r = (12 x 0.2) + (18 x 0.15) = 5.1
Here you are calculating the total 'tip' value, so you are separately finding the value of the tip for each of the friends.

You cannot combine the % and find the tip from the total money given, because they gave different amounts of money to the table, and different percentages of that, so they would give a different value for the tip each.

To find R% of the total cheque,
(5.1/18+12) x 100

This will give you the percentage of how much of the total they paid was 'tip'