Answer:
18
Explanation:
First simplify 15/45 to 1/3. Now think, what times the numerator, 1, equals 6? 1 times 6 is 6. Since you multiplied the numerator by 6, you also have to multiply the denominator, 3, by 6. 3 times 6 is 18. In other words, 1/3 = 6/18.