The formula for determining how long a hike will take is t=1/2(d+h) , where d is the distance in miles and h is the elevation gain in thousands of feet.

solve for h.

h=t−d/2

h=1/2 t−d

h=2d−t

h=2t−d

a complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is a solution of the equation x2 = −1. because no real number satisfies this equation, i is called an imaginary number. has no real solution, since the square of a real number cannot be negative.