(hope that helps )
ANSWER: 35
STEP BY STEP:
First rewrite the equation
(sry I cannot do exponents so I put the whole #) ⇩
3(x-1)2 + 2x -7 
Then substitute x for what it is, in this case 3. 
3(3-1)2 + 2x -7
Distribute
(9-3)2 + 2(3) - 7
Solve what is inside the parentheses 
6 2 + 2(3) - 7
Solve exponents
36 + 2(3) - 7
Solve multiplication 
36 + 6 - 7 
Add
42 - 7
Subtract for final answer 
35