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@dkmathstats how you reach 13 ?

From the 3 chocolates = 27, one chocolate piece is 3.

In the third line equation you have 2 chocolates pieces x 2 cupcakes = 12. You have 2 x 3 x (2 cupcakes) = 12. This would be 6 x 2 cupcakes = 12 which leads to 2 cupcakes being equal to 2. One cupcake would be 1.

In line one, the equation is donut x donut x cupcake = 16. The cupcake value is 1 which makes the donut equal to 4.

Use the known values to solve the final line with order of operations in mind.