Answer:
9° F
Step-by-step explanation:
We do 18 - 9 to get 9 ° F
That's a quadratic, a nice parabola in vertex form.
The parabola has a positive x^2 term, so it's a CUP, concave up positive. It will have a minimum at the vertex, which is (2,5). Plot that point.
Now we need a couple of guide points to draw the usual parabola going up from both sides of its vertex. We try x=0 giving (0,9) and see that x=4 also gives 9, (4,9). Plot the parabola through those two points and the vertex and you're done.
The Addition Property of Equality justifies Emily's first step. She added 9 to both sides, canceling out the minus 9 while keeping the equation equal.
The answer to your question is 4x-12
