Question 459890
The question is unclear.
Is the sum of the ages 56? 
the sum is 56
f+s=56
f+14=2*(s+14)
f=42 s=14
check
56=2 *28
ok
or is the difference between the ages 56?

the difference is 56

f-s=56
f+14=2*(s+14)
f=98
s=42
check 
98+14=112
42+14=56
112=2*56
ok