Convert each equation from slope-intercept form to standard form.
13.
15.
14.
16.
18.
17.
Solve each equation for the variable indicated.
19. The formula for the area of a triangle is .
Solve the equation for h.
20. The formula for the area of a trapezoid is .
Solve the equation for
.
21. The formula for the area of a circle is .
Solve the equation for r.
22. The formula for the volume of a cylinder is .
Solve the equation for h.
23. The formula for the volume of a pyramid is
Solve the equation for w.