Brian has started a savings account. the balance, g(x), in his account can be represented by the function g(x) = 25x + 350, where x is the number of weeks he deposits money. suppose 25 changed to 35. what does this mean in the context of the problem

For the answer to the question above, It means Brian is switching from saving $25 dollars a week to $35 dollars a week. Because every week Brian will add $25 to his savings account (In week 1, Brian adds $25. In week 2 Brian adds $50. And so on). So to change from 25 to 35 would mean that Brian is saving more money every week ($10 to be exact). 

And if you're curious, $350 stands for the amount of money Brian has initially (because at 0 weeks, Brian has $350 in his savings account). 

I hope this helps