The Alpitude is 5 because that is what the positive slope is. The Vertex is (2,6) because that is the lowest point on the graph. The equation is
y=5lx-2l-6 (lx-2l reprsents the absolute value of x-2)
Expand 8(5-r)/5=-2r as indicated: 40 - 8r
----------- = - 2r
5
Multiply both sides by 5, obtaining 40 - 8r = - 10r
Combine like terms: 40 = - 2r
Divide both sides by -2: -20 = r
The solution to 8(5-r)/5=-2r is -20. Verify this by subbing -20 for r in the given equation.