When solving this type of calculation you have to keep in mind that there is an order to follow.
Multiplications and divisions are to be solved first, addition and substraction are solved second.
If its easier for you to comprehend ir, you can think of the calculation as a sentence, where + and - act like a comma, dividing the sentence in terms.
[tex](6\cdot5)\text{ +( }\frac{30}{10})[/tex]
The calculation has two terms
[tex]6\cdot5\text{ and }\frac{30}{10}[/tex]
First you have to solve these terms
[tex]\begin{gathered} 6\cdot5=\text{ 30} \\ \frac{30\text{ }}{10}=\text{ 3} \end{gathered}[/tex]
Then you have to solve the addition
30 + 3 = 33
The error made in the calculation is that the addition was solved before the multiplication and division, making the student reach to an incorrect result.
