The answer of the above equation is 15.

Explaination:

Let the coke be, C

Let the burger be, Bu

& the French fires pack be, F

So, rewriting the equations in the form of above terms

Equation(1); C + C + C = 30

Equation(2); C + Bu + Bu = 20

Equation(3); Bu + 2F + 2F = 09

Equation(4); Bu + F * C = ??

Now, initiating from equation(1);

C + C + C = 30

3C = 30

C = 10

Substitute the value of C, in equation(2);

C + Bu + Bu = 20

10 + 2Bu = 20

2Bu = 10

Bu = 5

Similarly, substitute the value of Bu, in equation(3);

Bu + 2F + 2F = 09

5 + 4F = 09

4F = 4

F = 1

Now, for final equation(4), substitute all the equation values.

Bu + F * C = ??

= 5 + 1 * 10

= 15

Bu + F * C = 15