No because he will be $3.00 short.
So it is $0.75 a bottle. So then you multiply $0.75 by 20. You get $15.00
So David will not have enough in his wallet.
Answer:

Step-by-step explanation:
-5+2(10b-2)=31
Expand brackets.
-5+20b-4=31
-9+20b=31
Add 9 on both sides.
20b=40
Divide both sides by 20
b=2
Answer:
Step-by-step explanation:
5/1 - 5/7
35/7 - 5/7
= 30/7 = 4 2/7 lb
Multiply the denominators, 7 by 5,and 1 by 7. When you have the same denominator in each fraction you can subtract. (7x4= 28, 30-28= 2)