Answer:
10 - B = U
Step-by-step explanation:
U stands for the unopened bottles
for example if they opened 3 bottles it would be 10 - 3 = U (unopened bottles)
The value of U is 7 because the 10 bottles of water minus the 3 bottles they opened it would equal 7.
therefore the equation 10 - B = U shows the amount of unopened bottles