Grade 9 math linear equations

Question

An equilateral triangle has a perimeter of 17.85 metres. The side length of the triangle , in metres, is 2k - 0.5. What is the value of k ?

Answer 1

Since the triangle is equilateral we know that the sides are equal. Lets set up the equation;

There are 3 sides of 2k - 0.5, so

3( 2k - 0.5) = 17.85

2k - 0.5 = 17.85/3

2k = 17.85/3 - 0.5

k = (17.85/3 - 0.5) / 2