Answer:
a.
Step-by-step explanation:
5*(n-20)= (4n+4) / 2 is the equation, please say what you need answered.
Answer:
20 gallons were used from the tank with the octane rating of 80.
Step-by-step explanation:
Given : One tank of gasoline has an octane rating of 140 and another tank of gasoline has an octane rating of 80. To obtain a mixture of 60 gallons with an octane rating of 120.
To find : How many gallons should be used from the tank with the octane rating of 80?
Solution : Let x be the volume of gas whose octane rating is 140 and
y be the volume of gas whose octane rating is 80.
Then, we form the equation as:
(1) 

or
.........[3]
(2) 
Now multiply equation (2) by 4
...........[4]
Subtract (4) from (3)



Put x in equation [4] we get,





Therefore, x=40 and y=20
So, 20 gallons were used from the tank with the octane rating of 80.
Answer:
17
Step-by-step explanation:
2y+2=36
Let's solve this equation for 2y first. This means get 2y by itself.
So to get 2y by itself I need to undo that addition of 2 next to it.
The inverse operation of addition is subtraction.
I'm going to subtract 2 on both sides:
2y =36-2
2y =34
Now we want to get y by itself so we divide both sides by 2 since division and multiplication are inverse operations:
y= 34/2
y= 17