Answer:
16
Explanation:
If you flip 4 coins there are 16 possible outcomes
You can determine this by doing
x is 4 in this case
unless you want all the outcomes... I can answer that if you want
TTTT, TTTH, TTHT, THTT, HTTT, TTHH, THTH, HTHT, HHTT, THHT, HTTH, THHH, HTHH, HHTH, HHHT, HHHH