Do you mean y = mx + b instead of y = mc + b? In that case:
b in y = mx + b format is the y-intercept, as this kind of equation is called slope-intercept form.
To find that you first need to find what 9% is. You can multiply the number, 2,860 by .09 to find out your answer. That should be equal to 257.40. Since you now have that number, you can multiply it by 36. 257.40 is your average per month and you want to know by 3 years. So then your next step is 257.4*36 (there is 36 months in 3 years) which should be equal to 9,266.40.
The area would be 35 cm squared.
Lets break it down:
Triangle- The area of a triangle is base×height÷2
so if we plug in the numbers, the base would be 5 (the length) and the height would be 4 (the height). 5×4= 20÷2= 10.
Square- The area of a square is base×height so if we pluged in the numbers, the base is 5 (the length) and the height is 5 (the height). 5×5= 25.
10+25= 35 cm squared
Hope this helps!