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Day 5: Adding and Subtracting IntegersDescription: Continued practice in Adding and Subtracting Integers
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Objective: The purspose of this exercise is to continue creating and using formulas for word questions, using unfamiliar (negative) numbers.
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Example1:

Moscow is 17 degrees hotter than Leningrad.

If Moscow is 22 degrees, what temperature is Leningrad

(#Moscow) - (#hotter Moscow is)

 

(#Moscow) - (#hotter Moscow is)  

This is our formula.  It means take the value (how hot it is in Moscow) and Subtract (how much hotter moscow is).

Answer 1:

 (22) - (17)

=5

 

Moscow is 7 degrees hotter than Leningrad.  If moscow is 17 degrees what temperature is it in Leningrad.

Answer  (17) - (7)

= 10.

In this question we are told that Moscow is hotter than Leningrad.  So Leningrad is colder than Moscow.

So we start at the temperature moscow is (17) and go down by (7) to 10.

 

If Moscow was at 4 degrees, and we decrease by 7.  This is like the number of people on a bus increases by 4 and then decreases by 7.  Overall, more people have got off the bus, so the people on the bus has decreased by 3 overall.  i.e. the answer is -3.

If Moscow was at -6 degrees, and we decrease by 7.  This is like the number of people on a bus decreases by 6 and then decreases by another 7.  Overall, the number of people on the bus has decreased by 13 overall.  i.e. the answer is -13