let

d = the present age of Donna

b = the present age of Donna's brother

Donna is 12 years younger than her brother:

d = b - 12

In 2 years, she will be 14 years more than half as old as her brother:

d + 2 = 14 + (1/2)b

by solving the system of equations:

d = b - 12

d + 2 = 14 + (1/2)b

we find:

d = 36 years

b = 48 years

click here to see the step by step solution of the system of equations:

Donna is 36 years old now, and her bother is 48 years old now.