If F is Frank’s age now, he will be F+5 years old in five years’ time. John’s age now is 2(F+5)-5=2F+5.
Who is Uche? If Uche is represented by U then Dayo is U+15. No more info provided. Frank will be F+4 years old in 4 years’ time.
If John (Dayo) is 15 years older than Frank (Uche) then F+15=2F+5, F=10 and in 4 years, he will be 14.