Hi Jack. Did your teacher show you the word "BEDMAS"? It stans for
Brackets, Exponents, Division, Multiplication, Addition, Subtraction.

That's the order you should solve this kind of problem. Here's an example similar to yours:

What is 7(9-4)-4^2 ?

First we simplify the "B"rackets. (9-4) in the brackets becomes a 5.

7x5-4^2

Now we simplify the "E"xponents. 4^2 becomes 16.

7x5-16

Now we simplify "D"ivision. Oh, there's no division.
So we next do the "M"ultiplication. 7x5 becomes 35.

35-16.

And finally do the addition and subtraction. 35-16=19.

You can search our questions for the word BEDMAS to find other examples and explanations, but try your own question first to see if you can do it now.

Cheers,
Stephen La Rocque.