1) -9a + 8 = -10a - 2;
10a - 9a = -8 - 2;
a = -10;
2) 7m + 1 = 8m + 9;
7m - 8m = 9 - 1;
-m = 8;
m = -8;
3) 4 + 25y = 6 + 24y;
25y - 24y = 6 - 4;
y = 2.
1) -9a + 8 = -10a - 2;
10a - 9a = -8 - 2;
a = -10;
2) 7m + 1 = 8m + 9;
7m - 8m = 9 - 1;
-m = 8;
m = -8;
3) 4 + 25y = 6 + 24y;
25y - 24y = 6 - 4;
y = 2.