PLEASE HELP URGENT I'LL GIVE A LOT OF POINTS Find the explicit formula for the given sequence.

-4, 12, -36, 108,...

a
a_n=5·3^{n-1}

b
a_n=4·3^{n-1}

c
a_n=-4·(-3)^{n-1}

d
a_n=15·3^{n-1}

Pyotr tchaikovsky sporting goods operates on a 45% overhead based on the selling price, which results in an overhead of $65.34 on the newest version of an air hockey game set. if the air hockey game set costs pyotr tchaikovsky sports $49.32, find the selling price, the markup, and the net profit.