Answer:
The present age of the mother is 40 years
Explanation:
Let the age of the mother be M and that of the daughter D. Given that the mother is now 2 1/2 times old as her daughter Mary then
M = 2.5D
Given that Four years ago the ratio of their ages was 3:1
The mother's age 4 years ago was
= M - 4
and that of the daughter then was
= D - 4
Hence
(M - 4)/(D - 4) = 3/1
Cross multiply
M - 4 = 3(D - 4)
M - 4 = 3D - 12
M = 3D - 12 + 4
M = 3D - 8
Substitute into the first equation
3D - 8 = 2.5D
3D -2.5D = 8
0.5D = 8
D = 8/0.5
= 16 Years
M = 2.5D
M = 2.5 * 16
= 40 Years