Can you Solve this equation that went crazy all over the internet?

McDonald's Maths Algebra Riddle

15

Given
3Coke = 30 ....... Equation(1)
1Coke + 2 burger = 20 ....... Equation(2)
burger + 4 fries = 9 ....... Equation(3)
burger + fries * Coke = ?

Equation(1) => Coke = 10

Equation(2) => burger = (20-10)/2 = 5

Equation(3) => fries = (9-5)/4 = 1

Hence
burger + fries * Coke
= 5 + 1 * 10
= 5 + 10
= 15 ... Answer