if 11 a = 18 a + 21 find a + 9 =

Question

this question is really hard for me and i cannot wotk it out. can u please give me the answer? it will not be cheating. im only doing it for fun.

Answer 1

11 a = 18a + 21

 

0 = 18s + 21 - 11a

 

0 = 7a + 21

 

-21 = 7a

 

a = -21/7 = -3

 

 

CHECK:

   11(-3)= -33

 

  18(-3) + 21 = -54 + 21 = -33

 

So a = -3

 

a+9 = -3 + 9 = 6

Answer 2

11a=18a+21

0=7a+21=7(a+3)=7(a+9-6)

7(a+9)=7*6

a+9=6