HELP ME PLZZZ ASAP! Tyler’s work is incorrect. Explain the error he made.

Tyler is simplifying the expression 6 − 2x + 5 + 4x. Here is his work:
6 − 2 + 5 + 4
(6−2) + (5+4)
4 + 9
13

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Is there an x intercept in the equation 60*1.15^x

If a company produces x units of an item at a cost of $35 apiece the function c=35x is a of the total production costs