I guess this is the answer

then:

x=9
Answer:

Step-by-step explanation:
| Given
| Distribute the 2 inside the parentheses
| Add 10 to both sides
| Add. <em>Optional; not included in your question.</em>
<em />
<em> </em>| Divide by 2 on both sides.
<em />
<span>The cost of a service or item is an expense
</span>
-1 would be your answer. f(0) = -4. f(1) = f(0)+3 so f(1) = -1