Answer is A.
You start by adding the 7 to the opposite side. Giving you 19. You divide both sides by -2 which gives you x on one side and -9.5 on the other.
-2x-7=12
-2x=12(+7)
-2x=19
x=19/-2
x=-9.5
Answer:
14 and 16.
Step-by-step explanation:
We know that two consecutive even numbers is 30.
Let's let n be <em>any number</em>.
Then the first <em>even</em> number must be 2n.
This is because n can be any number, either even or odd. However, if we multiply it by 2, this <em>ensures</em> that 2n is even. Remember that any number multiplied by 2 yields an even number.
Therefore, the consecutive even number will be (2n+2). Not (2n+1), because that gives an odd number.
We know that they sum to 30. So, we can write the following equation.

And we solve from there:

So, the value of n is 7.
Therefore, the first even number is 7(2)=14.
And the consecutive even number is 16.
Edit: Typo
Answer:
2.871*10^9
Step-by-step explanation:
add a decimal point at the end of the number ( 2,871,000,000.) then count how many places it takes to move the decimal point between the first and second number (2.8) then write the rest of the numbers higher than "0" after, giving you the 2.871
to show that the number written is in scientific notation you add 10 to the power of the amount of times you moved the decimal place. In this case, because the decimal point was moved a total of 9 times, it would be 10 to the 9th power (10^9).
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