<span>2r ≤ 3(2r - 7)
</span><span>2r ≤ 6r - 21
</span><span>21 ≤ 6r - 2r
</span><span>21 ≤ 4r
</span><span>21/4 ≤ r
r</span>
21/4
r 5.25
</span><span>2r ≤ 6r - 21
</span><span>21 ≤ 6r - 2r
</span><span>21 ≤ 4r
</span><span>21/4 ≤ r
r</span>
r