Answer:
since we cant see what info is given maybe these tips can help...
the 'b' is also called the y-intercept, the y-int is what you start of with. Example, if your parents give you $20 and you spend $5 every week, your y-int is 20
The m is the slope, so if your parents give you $20 and you spend $5 every week, your slope is -5 because your money is decreasing at a linear rate
the x is the input, so if you want to know how much money you have 2 weeks after you got $20, you would substitute x with 2, and solve to get $10