Question 661570
Let k = Kurt's age and m = Mark's age.  From the first sentence we have
k = m - 12
From the second sentence we have:
m*1.2 + k*1.25 = 83
Substituting the first equation into the second gives:
m*1.2 + (m-12)*1.25 = 83
Expanding:
m*1.2 + m*1.25 - 15 = 83
m*2.45 - 15 = 83
m*2.45 = 98
m = 98 / 2.45 = 40
So Mark is 40 and Kurt is 28.