17. The current low temperature in uxbridge is 18 degrees Fahrenheit. Over the next two days the low temperature will decrease 12 degrees and increase 7 degrees. Express the temperature changes in a numerical expression and say what the temperature will be after three days. Numerical expression:

Expression: 18 - 12 + 7. In 3 days, the temperature will be 13 degrees.

Step-by-step explanation:

The temperature is 18 degrees.

It will decrease 12 degrees after one day. So, it is 18 - 12.

Then it will increase by 7 degrees after another day. So, it is 18 - 12 + 7.

18 - 12 = 6. 6 + 7 = 13.

So, the expression is 18 - 12 + 7 and the answer is 13 degrees (i think)

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.