let their present ages be 3X and 4X.
5 years ago, the ratio of their ages was 5 : 7,
Thus, (3x-5) : (4x-5) = 5 : 7.
Solving, we get X = 10.
Hence, their present ages are 3X = 30 and 4X = 40
If the current age of a person be y, then
- age after n years = y+ n
- age n years ago = y – n
- n times the age = ny
- If ages in the numerical are mentioned in ratio A : B, then A : B will be Ay and By