Using a 3x3 system, determine three numbers a, b, and c that satisfy the following conditions:
• the sum of the three numbers is 2.
• the sum of the first number, 5 times the second number, and 5 times the third number is -10.
• the sum of the first number, double the second number, and triple the third number is -3.

Use three variables a, b, c to write three equations. a = ( ), b = ( ) c = ( )