Question 1121882
let a = the age of sadia
let b = the age of ali
let c = the age of huma
let d = the age of naila


the average age of sadia, ali, and huma is 16 years old.
therefore a + b + c = 3 * 16 = 48


the average age of ali, huma, and naila is 12 years old.
therefore b + c + d = 3 * 12 = 36


sadia is 13 years old.
therefore a = 13


you have 2 equations that need to be solved simultaneously.


they are:


a + b + c = 48
b + c + d = 36


in the first equation, replace a with 13 to get 13 + b + c = 48 and solve for b + c to get b + c = 48 - 13 = 35


in the second equation, replace b + c with 35 to get 35 + d = 36 and solve for d to get d = 36 - 35 = 1


since d represents the age of naila, then naila must be 1 year old.





subtract 13 from both sides of each equation and combine like terms to get:


b + c = 48 - 13 = 35
b + d = 36 - 13 = 20