Question 928793
5a-5b+5c=25
<u>-a+ b-5c=-21</u>
4a - 4b = 4
.........5a-5b+5c=25 0r a-b+c= 5 ***
2(a-b+c= 5)
<u>-4a+4b-2c=-12</u>
-2a + 2b = -2
.......
4a - 4b = 4
<u>2(-2a + 2b = -2)</u>
0 = 0
Infinite Solutions: 4a - 4b = 4  0r a - b = 1  
Re TY:  Note: Using b = a-1
b = a-1,  c = b-a+5  0r c = (a-1) - a + 5 = 4
(a, a-1, 4)