Answer:
Step-by-step explanation:
John's age = w
His brother's age = 2*w = 2w
His sister's age = 16 years
Total age of all siblings = 31
w + 16 + 2w = 31
w + 2w + 16 = 31
Combine like terms
3w + 16 = 31
Subtract 16 from both sides
3w = 31 - 16
3w = 15
w = 15/3
w = 5
His brother's age = 2w
= 2*5
= 10