Answer:
$5.40
Step-by-step explanation:
First, figure out the cost of the items with tax; for Tommy we have 20*0.08 = 1.6, add that 1.6 to the 20 and his purchase is $21.6, for John we have 25*0.08 = 2, add 2 to his 25 and his purchase is $27. To find the difference we subtract 27-21.6 = 5.4 or $5.40
Answer: Choice D

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Explanation:
The left portion is the interval (-∞, -2)
This is a shorthand way of saying 
The curved parenthesis says "do not include this endpoint as part of the solution set". Note the open hole at x = -2 in the diagram.
In contrast, the value x = 4 is included (due to the filled in circle), so we use a square bracket for this endpoint. Therefore, the right-hand portion is represented by [4, ∞) which translates to 
Negative and positive infinity will always use a parenthesis, and never a square bracket. This is because we can only approach infinity but never reach it, so we cannot include it as an endpoint.
All of this builds up to the full interval notation to be 
The only square bracket is near the 4; everything else is a curved parenthesis. This is why choice D is the final answer.
Answer:
17e+18
Step-by-step explanation:
9e+4=-5e+14+13e
4e+4+14+13e
17e+4+14
17e+18
cuatro no? porque osea tiene q