To work out the average speed you would have to use the formula
AS = 15.0 ÷ 30.0 = 0.5 which is distance divided by time.
The you would do 0.5 x 60 = 30 (60 minutes = 1 hour)
So the average speed would be 30.0 km/h.
30 (miles) times 4 (hours) equals to 120 miles. 400 miles minus 120 miles equals 280 miles (distance the other car has driven). 280 divided by 4 (because we want to find the speed for only one hour) equals 70 miles.
The average speed of the other car is 70 mph
Answer:
x=10 and y=12
Step-by-step explanation:
To solve this quadratic equation we will use two method
1. Elimination method
2. substitution method
first of we use elimination method
we either eliminate x or y
we will be eliminating y
83x-20y=590..........(eq1)
60x+18y=816...........(eq2)
y will be eliminated by multiplying
(eq1) by 9
(eq2) by 10
which will give
747x-180y=5310.........(eq3)
600x-180y=8160.........(eq4)
see that y has the same value that is (-180y and +180y)
so to eliminate y completely you have to add eq1 and eq2 because if you don't add them together you wont eliminate y
747x-180y=5310
+
600x+180y=8160
=
1347x+0=13470
1347x=13470
x=13470/1347
x=10
Now to find y we use substitution method ie put x=10 in any of the equation above(eq1,eq2,eq3, eq4) you will get the same answer
eq1
83x-20y=590..... where (x=10)
83(10)-20y =590
830-20y=590
like terms
-20y=590-830
-20y= -240
divide both sides with -20
y= -240/-20
y=12
OR
eq2
60x+18y=816..... where x=10
60(10)+18y=816
600+18y=816
like term
18y=816-600
18y=216
y=216/18
y= 12
or eq3 or eq4 you will still get the same answer......
7 2/3 divided by 1 1/3 =
= (7 2/3) / (1 1/3)
= (23/3) / (4/3)
= 23/3 * 3/4
= 69/12
= 23/4
= 5 3/4
= 5 9/12
17,900 * (1 -0.13)^7 = 6752.86 . . . . dollars
