Substitution problems

im in desperate need of your help! Solving linear Equations by Substitution.

1. x - 3y = 114
3x + 7y = -154
(a) (21, -31)
(b) (-31, 21)
(c) (4, 12)

2. 19x - 10y = -269
19x - 12y = -243
(a) (2, -27)
(b) (19, 37)
(c) (-21, -13)

3. 57x = 972 + 3y
-y = -398 + 19x
(a) (-3, 14)
(b) (19, 37)
(c) (-16, 4)

4. 8x - 11y = 244
24 + 3y = x
(a) (36, 4)
(b) (-2, -13)
(c) (30, 29)

please help mathematicians!

(1)

x - 3y = 114
3x + 7y = -154

x = 3y + 114

3x + 7y = -154
3(3y + 114) + 7y = -154
9y + 342 + 7y = -154
16y + 342 = -154
16y = -496
y = -31
x = 21

The answer is (a) = (21, -31).


(2)

19x - 10y = -269
19x - 12y = -243

19x = 10y - 269

19x - 12y = -243
(10y - 269) - 12y = -243
-2y -269 = -243
-2y = 26
y = -13
x = -21

The answer is (c) = (-21, -13).


(3)

57x = 972 + 3y
-y = -398 + 19x

y = 398 - 19x

57x = 972 + 3y
57x = 972 + 3(398 - 19x)
57x = 972 + 1194 - 57x
114x = 2166
x = 19
y = 37

The answer is (b) = (19, 37).


(4)

8x - 11y = 244
24 + 3y = x

x = 3y + 24

8x - 11y = 244
8(3y + 24) - 11y = 244
24y + 192 - 11y = 244
13y + 192 = 244
13y = 52
y = 4
x = 36

The answer is (a) = (36, 4).



Hope this helps...good luck!