Brainlest and points math question

Compare the cost of the bike trips from the two companies shown.for both the cost in a linear function of the number of days which statements is true

Estimate the area under the curve f(x) = 16 - x^2 from x = 0 to x = 3 by using three inscribed (under the curve) rectangles. answer to the nearest integer.

Solve the equation.then check your solution 8=1.88+a