Answer: 
You can write this as (-infinity, 7) if you aren't able to use the infinity symbol.
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Explanation:
Think of x < 7 as writing 
So x is between negative infinity and 7, excluding both endpoints.
To write
in interval notation, we write
The curved parenthesis tell us to exclude the endpoint.
So basically you have to see how the person is built but in average it will took like 12minutes
Solution:
1x +2x -7 =0
3x-7=0
Add 7 To Both Sides Of The Equal Sign Then Divide By 3