3x10^5
+7x10^4
+7x10^3
+0x10^2
+6x10^1
+0x10^0
Find the pattern. 184-164 gets you 20. so 84 - 20 is your answer
To solve for c, you need to get c onto one side of the equation, or make it c=__. So what I would do first is subtract a/b from both sides
a/b + c = d/c
-a/b
a/b - a/b + c = d/c - a/b
c = d/c-a/b
The bottoms are all multiples of seven