I added them together, first the 9-10 year olds and the 11-12 year olds. There were 15, then added on the 13-14 ear olds, making altogether 21 kids over the age of 8
What you must do for this case is subtract both quantities and verify the final result. We have then: 15 3 / 10-13 9/10 = Rewriting 15.3 - 13.9 = 1.4 = 1 4/10 answer: this month fell 1 4/10 more centimeters of rain
