Simple....

x<6
This means that on your graph at 6 it's a circle (not colored in) and it goes to the left indefinitely...
Thus, your answer.
Answer:
(-∞, -5/2) ∪ (1, ∞)
Step-by-step explanation:
"Increasing" means the graph goes up to the right. It is increasing from the left up to the local maximum--the peak at left.
It is increasing again from the local minimum on the right to the right side of the graph.
The two sections where the graph is increasing are ...
(-∞, -5/2) ∪ (1, ∞)
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The graph is <em>decreasing</em> between the maximum on the left and the minimum on the right.
Nathaniel's total cost is $(3.50 x2 + 3.25 x4 +1.90 x2 +1.20) = $24 he got 5% off so he paid $24- (24* 5/100) =$22.80