Question

2x+y+2z=25
3x-y+6z=48
5x+2y+4z=55

I got stuck after step 2 of trying to eliminate the first two equations where do I go from their and would kindly like full explanation of how to solve it so I can practice it out. Thank you :)

Answer 1

If you want to see the details of elimination, a good place to go is

http://www.gregthatcher.com/Mathematics/GaussJordan.aspx

Answer 2

A preliminary glance at the coefficients tells you that the y's would be the easiest to eliminate.

As a matter of fact, you can do it in your head:
add the first two equations:
5x + 8z = 73 , #4

mentally double the 2nd and add to the third:
11x + 16z = 151 , #5

double #4 ---> 10x + 16z = 146
subtract from #5
------> x = 5

back in #4
25+8z = 73
8z =48
z = 6

back in #1
2x+y+2z = 25
10 + y + 12 = 25
y = 3