What is the ratio in its simplest form? <br> 3 : 6 : 18 = <input min="0" type="number" id ="imp5pg090q1a_1" class="lineinput" placeholder="?" /> : <input min="0" type="number" id ="imp5pg090q1a_2" class="lineinput" placeholder="?" /> : <input min="0" type="number" id ="imp5pg090q1a_3" class="lineinput" placeholder="?" />