ok only 3 questions and going to sleep
WILL MARK BRAINLIEST

Answer:
71.2
Step-by-step explanation:
PEMDAS is Parentheses, Exponent, Multiplication, Addition, Subtraction
This is just the order you do the operations.
First, Parentheses.
Second, Exponents,
Third, Multiplication or Division
Last, Addition or Subtraction
So, in 6 x (2.4 + 10.3) - 5
We first do parentheses which is
(2.4 + 10.3) = 12.7
Now we have,
6 x 12.7 - 5
The next thing is multiplication
6 x 12.7 = 76.2
Now we have,
76.2 - 5
Lastly subtract,
76.2 - 5 = 71.2