SOLUTION: 1.Two airplanes leave Chicago at the same time and fly in opposite dirrections. If one travels at 450 miles per hour and the other at 550 miles per hour, how long will it take for
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Question 136194: 1.Two airplanes leave Chicago at the same time and fly in opposite dirrections. If one travels at 450 miles per hour and the other at 550 miles per hour, how long will it take for them to be 4000 miles apart? (Solve in algebraic equations)
2.Bret started on a 70 mile bicycle ride at 20 miles per hour. After a time he became a little tired and slowed down to 12 miles per hour for the rest of the trip. The entire trip of 70 miles took 4 1/2 hours. How far had Bret ridden when he reduced his speed to 12 miles per hour?
3. Suppose that you have a supply of a 30% solution of alcohol and a 70% solution of alcohol. how many quarts of each should be mixed to produce 20 quarts that is 40% alcohol? Found 2 solutions by checkley77, ankor@dixie-net.com:Answer by checkley77(12844) (Show Source):
You can put this solution on YOUR website! 450t+550t=4,000
1000t=4000
t=4000/1000
t=4 hours they will be 4,000 apart.
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20t+12(4.5-t)=70
20t+54-12t=70
8t=70-54
8t=16
t=16/8
t=2 hours @ 20 mph.
proof
20*2+12(4.5-2)=70
40+12(2.5)=70
40+30=70
70=70
You can put this solution on YOUR website! I'm going to give you the equation for each problem
:
1.Two airplanes leave Chicago at the same time and fly in opposite directions. If one travels at 450 miles per hour and the other at 550 miles per hour, how long will it take for them to be 4000 miles apart? (Solve in algebraic equations)
t = time (in hrs) for them to be 4000 mi
450t + 550t = 4000
:
:
2.Bret started on a 70 mile bicycle ride at 20 miles per hour. After a time he became a little tired and slowed down to 12 miles per hour for the rest of the trip. The entire trip of 70 miles took 4 1/2 hours. How far had Bret ridden when he reduced his speed to 12 miles per hour?
:
d = distance ridden at 20 mph
then
(70-d) = distance ridden at 12 mph
:
Time = dist/speed
: + = 4.5
:
:
3. Suppose that you have a supply of a 30% solution of alcohol and a 70% solution of alcohol. how many quarts of each should be mixed to produce 20 quarts that is 40% alcohol?
;
let x = amt of 70% alcohol
then
(20-x) = amt of 30% alcohol
:
.70x + .30(20-x) = .40(20)
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