A suit case measures 24 inches long and the diagonal is 26 inches long. How much material is needed to cover one side of the suitcase? You are looking for a leg

It helps to draw diagrams when working through problems like this.  

Given a rectangular prism (the suitcase), drawing a diagonal through its side will give you two right triangles.  You can use the Pythagorean Theorem (a² + b² = c², where c is the hypotenuse of a right triangle) to find the length of the unknown side.  The hypotenuse of the triangle is the diagonal since it is the longest side, and it is opposite the right angle.

a² + b² = c²

a² + 24² = 26²

a² + 576 = 676

a² = 100

a = 10 in

Remember that this is only the side length of the triangle.  To find the amount of material needed to cover one side of the suitcase, we need its area.  We can find the area using the formula for area of a rectangle: A = bh.

A = bh

A = 10*24

A = 240 in²

240 in²

the solution is 12x-6y