Precalculus (6th Edition)

$\color{blue}{\dfrac{2}{3}}$
Factor the numerator and the denominator then cancel the common factors to obtain: $\require{cancel} =\dfrac{10(2r+1)}{15(2r+1)} \\=\dfrac{\cancel{10}^2\cancel{(2r+1)}}{\cancel{15}^3\cancel{(2r+1)}} \\=\color{blue}{\dfrac{2}{3}}$