-21 = 9a - 15 - 3a -6 = 6a -1 = a
It is: 9a-a-a = 7a
-(a + 6)(a + 3)
If: 9a = 18b Then: a = 2b
a = 6b = 9a + b = 6 + 9 = 15
a= -0.8
9a+21 3(3a+7)
Collect like terms: 9a -7a = 9 - 15, ie 2a = -6, so a = -3
2a+5a+9a = 16a
-14 + 9a = 389a = 52a = 52/9 or 5.78
10
12a + 6b + 9a + 14b =(12a + 9a) + (6b + 14b) =21a + 20b