Question

The temperature outside dropped 13°F in 7 hours. The final temperature was -2°F. What was the starting temperature?

Answer 1

`color(brown)(x = 13 - 2 = 11^@` `color(brown)(F`

Explanation:

Let the original temperature be `I = x`.

Final temperature `F = -2^@`

Change in temperature `C = I- F =x - (-2) = (x + 2)^@ F`

But it’s given change in temperature `C = 13^@F`

Hence, `C = 13 = ( x + 2)`

`:. x + 2 = 13` or `color(brown)(x = 13 - 2 = 11^@` `color(brown)(F`

Answer 2

`-2+13=11^@`F

Explanation:

Another way to approach this question, without algebra, is to approach it this way:

We know that at the end of the time period, it's `-2^@`F. At the beginning of the time period, it was `13^@`F warmer. And so we can say that the temperature at the beginning of the time period can be found by adding `-2` and `13`:

`-2+13=11^@`F