Have you learned PEMDAS? (Parenthesis, exponents, multiplication, division, addition, subtraction). That is what I am going to do here.
The first parenthesis, let's solve. 7*10=70-5=65
The second parentheisis: I am assuming the negative sign is a typo, and this answer will be off if it is not. Sorry. 5*10=50
65*50=3250
I hope this helps, and let me know if you need further assistance.