We are told that Sarina's piano teacher gave her a large candy bar
The candy bar has 2 and 1/2 servings and one serving has a mass of 39 grams.
We wsnt to determine the mass of the whole candy bar.
The mass of the candy bar can be found to be equal to;
Therefore, we get the mass of the candy bar as;
[tex]2\frac{1}{2}\times39=\frac{5}{2}\times39=97.5[/tex]Therefore, the mass of the candy bar is 97.5 grams
