The system of equations y equals 1/4 x minus one and y equals -1/2 x -1/4 as shown on the grap

Simplify 15(x - 4)(x -1)-3(x + 4)(x - 1) with steps

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

Ahiker stands at an unknown elevation before he ascends 2 miles up a mountain to an elevation of 9 miles. find the elevation of the hiker before his ascent.