Question

(5a-2)(5a+2)-3(1-a)-3a=

Answer 1

So first we need to know the order of operations
P - Parenthesis
E - Exponents
M - Multiplication
D - Division
A - Addition
S - Subtraction

Then the special cases:
(I have attached a picture below)

Lets get into action!
(5a - 2)(5a + 2) - 3( 1 - a ) - 3a 
25a² - 4 - 3 + 3a - 3a 
25a² - 7 
25a² - 7 is the answer

Answer 2

Hi There! :)

(5a-2)(5a+2)-3(1-a)-3a=25a2−7

Therefore answer is 25a2−7