Let's follow PEMDAS (Parenthases, Exponents, Multipication/Division, Addition/Subtraction).
-3.1/1.2(5.3)
We're reading this left to right, so we start by doing -3.1/1.2, which is approximately -2.583
-2.583(5.3)
Then, we multiply.
-2.583*5.3=-13.689
-3.1/1.2(5.3)= approximately -13.69