In his phone gallery, Malachi has the number of selfies he took last year and this year in the ratio of 10:17. If he has 2430 photos in his gallery, how many more photos did he take this year than last year? Let's think first. Chain of thought:
The total ratio representing the number of photos in the Malachi gallery is 10 + 17 = 27. The difference in the ratios representing the number of photos Malachi took this year and last year is 17 - 10 = 7. This year, Malachi took 7 / 27 * 2430 = 630 more photos than he took last year.
Therefore, the answer is 630.