Try using PEMDAS
Paranthesis
Exponents
Multiplication
Division
Addition
Subtraction
First do P: 20 +12 = 32
4 - 3 = 1
Now the new equation is 4(32) ÷ 1
Since there are no exponents, we go straight to the multiplication:
4 x 32 = 128
Now we have 128 ÷ 1 which equals 128
So your answer is 128 :D
