The answer is 90 because 360/4 (since it is a quadrilateral) is 90 degrees
Volume of the box = length ^ 3 = 5^3 = 125 cubic inches
Volume of rectangular prism = length x width x height = 3 x 4 x 18 = 216 cubic inches
Volume of entire sculpture = volume of box + volume of rectangular prism = 125 + 216 = 341 cubic inches.
Slope-intercept form looks like this: y = mx + b. For your equation, simply add 3x on both sides: y = 3x + 19.