Answer:
the price for one pretzel was $1.75
Step-by-step explanation:
d for drinks
p for pretzel
3d + 3p = 9
3d = 9 -3p
d = 3 - p
replace d = 3 - 9 into 4d + 2p = 8.5
4d + 2p = 8.5
4(3 - p) + 2p = 8.5
12 - 4p + 2p = 8.5
-2p = 8.5 - 12
-2p = -3.5
p = 1.75