How do I write this as an expression?

Bob bought 5 skirts at $x each. 3 of the 5 skirts came with a matching top for an additional $9 each. Write and simplify an expression that represents the total cost of her purchase.
Update: Ok second question...
Find the value of y that makes each equation true for all values of x
3x+6x=yx
x+5+11x=12x+y
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