X = number of cds on the rack
x + 7 = 30
x = 30 - 7
x = 23 <== so there are currently 23 cds on the rack
The question asks, "how many kilometers of road did they build each day?"
This means: kilometers per day
kilometers/days
(635 kilometers)/(3 days)
635/3 kilometers/day
211 2/3 kilometers/day
I think the answer its 1.8 percent because if you subtract 15-13.2 comes out to be 1.8.
but l also think it could be 12 percent error.
As written, it is interpreted to mean 14·22·350·x = 107800x.
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Often such an expression written here on Brainly is expected to be interpreted as an exponential expression: 
Just copy this down. you welcome