Answer:
Precambrian period
Step-by-step explanation:
Since the Great oxidation period = 2.4 Billion years ago era = Precambrian period.
Micro-fossils attributed to cyanobacteria are abundant during the Proterozoic that came later 2,5 billion years ago and ended 540 million years ago,
Answer:
x = -122/13 OR 9.3846
Step-by-step explanation:
First, take a look at the second equation. Add 8x to the other side.
-7y= 8x -18
Then, divide by -7 to get a regular "y=" equation.
y= 8/7x -18/7
Move on the the first equation. Let's get "y" by itself. Add 3x to the other side.
y= 3x +15
Considering both equations are equal to Y, set them equal ( except the "y" part )
8/7x - 18/7 = 3x + 15
Multiply all by seven so that there are no fractions.
8x - 18 = 21x + 105
Subtract 8x from both sides.
-17 = 13x + 105
Subtract 105 from both sides.
-122 = 13x
Divide by 13 on both sides.
x = 9.3846
Or if you don't want decimals, just say x = -122/13
Quick Note: I made a mistake. I had looked at the second equation at -18. The answer is incorrect but the method of solving is correct. Also, make sure to plug in the value of x to get Y.
Step-by-step explanation:
1x+2x+3x=60
x=10
2x+3x+4x=20+30+40=90
average=90÷3=30
Answer:
Step-by-step explanation:
The median is the average of the lengths of the two bases:
5x -20 = (12 + (4x -10))/2
5x -20 = 2x +1
3x = 21 . . . . . add 20-2x
x = 7
Then the lengths are ...
median = 5x -20 = 5·7 -20 = 15
base = 4x -10 = 4·7 -10 = 18
