Answer:
w = 5, x = 7, y = 6, z = 12
Explanation:
Evaluate each row by solving the corresponding equation, that is
row 1
4w = 20 ( divide both sides by 4 )
w = 5
row 2
2w + 2x = 24 ( substitute w = 5 )
2(5) + 2x = 24
10 + 2x = 24 ( subtract 10 from both sides )
2x = 14 ( divide both sides by 2 )
x = 7
row 3
w + 2x + y = 25 , that is
5 + 2(7) + y = 25
5 + 14 + y = 25
19 + y = 25 ( subtract 19 from both sides )
y = 6
row 4
w + x + y + z = 30 , that is
5 + 7 + 6 + z = 30
18 + z = 30 ( subtract 18 from both sides )
z = 12