Explanation:
You use PEMDAS parenthesis, exponents, multiplication, addition, subtraction.
First you will change the -(-3) into positive
-55+-7x6+3x4
Now change the +-7 into negative 7
-55-7x6+3x4
Now multiply 7 times 6...
-55-42+3x4
Now multiply 3 times 4...
-55-42+12
Now add the two negatives, 55 and 42
-97+12
Now add those...
-85