Question

Octavia is asking about her age. My brother is 7 years older than I am. Our ages add up to 39. How old are Octavia and her brother?

Answer 1

If we want to figure out the ages of Octavia and her brother we will need to check our information.
their ages add up to 39 and her brother is 7 years older than her 
first you will think of all numbers that equal 39; 1+38, 2+37, 3+36, 4+35, 5+34, 6+33, 7+32, 8+31, 9+30, 10+29, 11+28, 12+27, 13+26, 14+25, 15+24, 16+23, 17+22, 18+21,and 19+20
then  eliminate all the numbers that don't have a difference of 7 which will leave the following; the only numbers left are 16 and 23 

so that means that her brother is 23 and Octavia is 16