The fence around a quadrilateral-shaped pasture is 3a^2+15a+9 long. three sides of the fence have the following lengths: 5a, 10a-2, a^2-7. what is the length of the fourth side of the fence?
Sally deposited money into a savings account paying 4% simple interest per year. the first year, she earn $75 in interest. how much interest will she earn during the following year?