Answer:

Step-by-step explanation:
so first find the common denominator which is 162
so on 4/9 multiply 18 to denominater and numerator which makes it 72/162
next multiply 9 to numerator and denominator in 13/18 which makes it 117/162
so now add:

so now simplification.
189/162 can be reduced by 3
63/54 is our new answer. now we can reduce it by 9
7/6 is our new answer. now we must change it to a mixed number which is 
hope this helped!
Answer:
its 6 7/8
Step-by-step explanation:
You can subtract 4 from 13 then subtract 4 again
This is very simple, all you have to do is subtract 18 and 6 and that would be 12, and now we have 12 as a POSSIBLE answer, lets check our work to be 100% correct so now try to add 12 and 6 and we get 18, so yay it made the equation true and since its true its right so that's the answer.
Answer: c = 12 so 18 = 12 + 6 is true.