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:
B. false
Step-by-step explanation:
Square units
I hope that is useful for you :)
Answer:
For chess club:
y1 = 16 + 1*x where y1=total number of members after x months
For film club
y2 = 4 + 4*x where y2=total number of members after x months
y1 = y2 at
16 + x = 4 + 4x
3x = 12
x = 4
Therefore, after 4 months they the same number of members (equals 20 members, 16 + 1*4 or 4 + 4*4).