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.
The monthly rent of the apartment is x = 1310 dollars a month
Answer:
<u>1035 feet</u>
Step-by-step explanation:
Taking the tan ratio of the angle of elevation :
- tan 49° = h/900
- 1.15 = h/900
- h = 1.15 × 900
- h = <u>1035 feet</u>
I think the awnser is B=30