When dealing with radicals (also known as square roots) the rule of the arithmetic standard process is the same for expressions within parentheses and radicals. I learned the process as:
"Please Excuse My Dear Aunt Sally" to simplify expressions
"Parentheses, Exponents, Multiple, Divide, Add, Subtract"
The problem stated can be written as:
3 X √(2 + 5). Reading the expression from Left to Right,
1st Simplify expressions within Parentheses, in this case 2 + 5 = 7,
Our original expression is now : 3 X √7
As a teacher I accept 3√7 as the simplified answer.
For the digital answer, now that we completed all Parentheses, will look from Left to Right for all Exponential expressions.
We know that √7 can also be stated as 7(1/2); Solving we get 2.645751311.
Our original expression is now 3 X 2645751311, which when multiplied gives us:
The Answer = 7.93725933