Just so you understand more deeply. There is more than one answer for this question, "as it is written". Math can be like this sometimes. And it can cause a lot of confusion. You must read it very carefully. If you multiply 8 x 4 you get 32. You know that (? x 7) must be greater that that number because you subtract (? x 3). If you multiply 5 x 7 you get 35. And that is greater than 32. Then take 32 from 35 to get 3. So that (5 x 7) - (1 x 3) also gives 32. If ? is assumed to be the same value for both (? x 7) and (? x 3). Then the problem can be solved by the rules of algebra, as it was done by Vivian. Any other analysis can give you other possible answers. If this is the case, then there must be some more to the question. You are not told that ? = ?. But this must be the case. And ? is an "operator", not just a question mark. To get just one answer, they must both be 8. You just use the "math rules" to move things around until you find the way to the answer. Scientists sometimes do this for months or years to solve complicated problems.
Often, your number sense gets confused by this kind of "discrepancy" or not knowing where to start situation, when you go beyond simple math and into algebra concepts. And this can leave you lost and not knowing where to start. If the general question is put to you to solve the problem by algebra concepts. You can assume more into the question by applying the rules of algebra. In algebra, symbols are used instead of numbers. This is part of the "math rules". Then the other rules are used to find the answer. The symbol ? is just as valid as x or y or whatever. In science you sometimes even use words. (That is how word problems are built.) Once you know the "math rules". You can apply logic to solve math problems.
I send this answer to give you a deeper understanding of what you are doing. You are learning basic rules now. Knowing what is causing your confusion can make things easier in the future. Jut play with the "ok" math maneuvers (+, -, multiplication, division) until you can do them without thinking. And math will become easy. There are more "math rules" that you will learn later. You will "see" the answers easier later. After you get more experience. Don't expect this now. The key to easy math is practice.