1) 2x + 9 = 13 - x;
2x + x = 13 - 9;
3x = 4;
x = 1 1/3;
2) 0.5a + 11 = 4 - 3a;
0.5a + 3a = 4 - 11;
3.5a = -7;
a = -2.
1) 2x + 9 = 13 - x;
2x + x = 13 - 9;
3x = 4;
x = 1 1/3;
2) 0.5a + 11 = 4 - 3a;
0.5a + 3a = 4 - 11;
3.5a = -7;
a = -2.