20$ divided by 8.7 gallons=$2.30
30$ divided by 12.4 gallons=$2.41
Yola got the better deal
Y-4X =3 ; 2x-3y=21
Y= 3+ 4x
2x -3( 3+4x)= 21
2x- 9- 12x= 21
-10x -9= 21
-10x -9+9= 21+9
-10x = 30
X= 30/-10= -3
Y= 3+4x = 3+ 4* (-3)= 3-12= -9
Answer:
About 700 billion bacteria
Step-by-step explanation:
Given
![1oz \approx 28g](https://tex.z-dn.net/?f=1oz%20%5Capprox%2028g)
![1g = 25\ billion\ bacteria](https://tex.z-dn.net/?f=1g%20%3D%2025%5C%20billion%5C%20bacteria)
Required
Number of bacteria in 1 oz
![1g = 25\ billion\ bacteria](https://tex.z-dn.net/?f=1g%20%3D%2025%5C%20billion%5C%20bacteria)
Multiply both sides by 28
![28 * 1g = 25\ billion\ bacteria * 28](https://tex.z-dn.net/?f=28%20%2A%201g%20%3D%2025%5C%20billion%5C%20bacteria%20%2A%2028)
![28g = 700\ billion\ bacteria](https://tex.z-dn.net/?f=28g%20%3D%20700%5C%20billion%5C%20bacteria)
Recall that
![1oz \approx 28g](https://tex.z-dn.net/?f=1oz%20%5Capprox%2028g)
This means:
![1oz \approx 700\ billion\ bacteria](https://tex.z-dn.net/?f=1oz%20%5Capprox%20700%5C%20billion%5C%20bacteria)