Answer:
84
Step-by-step explanation:
Let the first digit = x
Let the second digit =y
x + y = 12
x + 4 = 3*y
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From the second equation, we learn that x = 3y - 4
Put that into the first equation.
3y - 4 + y = 12 Combine the left side
4y - 4 = 12 Add 4 to both sides
4y = 16 Divide by 4
4y/4 = 16/4
y = 4
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x + 4 = 12
x + 4 - 4 = 12-4
x = 8
So the number is 84
The answer is 20 just plug your choices in to get which one works!
We can set this problem up as an algebraic equation, which we can then solve to find our answer.
We start at -3. So we can start our equation with that:
However, this doesn't represent any change in temperature, just that we start at -3. To show change, we will use the variable , where stands for the number of hours. Each hour accounts for a change of -2.5 in degrees, meaning that we must multiply our by -2.5. We can now add this term into our equation:
We are trying to find when we will reach -18 degrees, so we will set our entire equation equal to -18 and solve:
It will take us 6 hours, or choice A.