First, let's cancel out the x by multiplying 2x + 18y = -9 by -2.
-2 ( 2x + 18y = -9) = -4x -36y = 18
Then, we combine the two equations.
-4x + 4x = 0
18y - 36y = -18y
-27 + 18 = -9
Our new equation is -18y = -9.
Now, divide both sides by -18.
-18y / -18 = y
-9/ -18 = 1/2
y = 1/2
We can plug in a value for y since y = 1/2 now.
Let's use 2x + 18y = -9
Plug in y.
2x + 18(1/2) = -9
2x + 9 = -9
Then, subtract 9 from both sides.
2x = -18
Divide by 2.
2x/2 = x
-18/2 = -9
x = -9
Lastly, we can plug in both x and y values to see it works.
2(-9) + 18(1/2) = -9
-18 + 9 = -9
Therefore, the values of x and y does work.
x = -9
y = 1/2
Answer:
Total cost is $100.41 ( $93.84 + $6.57)
Step-by-step explanation:
Thinking Point: The total cost is the cost of the items PLUS the tax. 93.84 ∙ 0.07 = 6.5688 (round to “cents”) = $6.57
Hope this helped!
Let:
v = Olga's speed
t = the time Anna spent going to school (3 km/hour)
t/2 = the time Anna spent running back home with speed of 6 km/hour
So, t + t/2 = 3t/2 is the total time
In the meantime distance = speed*time and the both made the same distance we can put it as:
3t + 6*(t/2) = (3t/2)*v
6t = (3/2)tv divide both sides by t
(3/2)v = 6
v = 2*6/3
v = 4 km/hour
Olga's speed was 4 km/hour.
