Answer:
24
Step-by-step explanation:
all odd numbers possible: 1, 3, 5, 7
__ __ __ __
there are 4 possibilities for the first blank
for the second blank there are 4-1 = 3 possibilities as one of the numbers will have been used
for the third blank there are 4-2 = 2 possibilities as 2 of the numbers have been used
for the last blank there is only 1 possibility
so the number of solutions possible is 4 x 3 x 2 x 1 = 24