we have
5 · 4 · -3 + 10 ÷ 2
Applying PEMDAS
P ----> Parentheses first
E -----> Exponents (Powers and Square Roots, etc.)
MD ----> Multiplication and Division (left-to-right)
AS ----> Addition and Subtraction (left-to-right)
step 1
Multiplication
5.4.-3=-60
substitute
-60+10÷ 2
step 2
Division
10÷ 2=5
substitute
-60+5
step 3
Addition
-55
therefore
option B