Q: In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Problem: if a - b = 10 and a ^ 2 + b ^ 2 = 150 , find the value of ab 
Options: a ) 10 , b ) 12 , c ) 25 , d ) 18 , e ) 19
A:
c