A football game was played between two teams, the Cougars and the Panthers. The two teams scored a total of points, and the Cougars won by a margin of points. How many points did the Panthers score?
- A)
- B)
- C)
- D)
- E)
Answer
A
Key insight
Sum and difference are given, so the smaller score is half of (sum minus difference): (34 - 14)/2 = 10.
Solution
Let and be the Cougars' and Panthers' scores. We know and .
Subtracting the second equation from the first eliminates :
(Then , and indeed and .)
The Panthers scored .
Why this works
Whenever two quantities have a known sum and known difference , the larger is and the smaller is . Memorizing this pattern turns a whole class of word problems into one line of arithmetic.
The trap
Reporting the Cougars' score 24 instead of the Panthers' score, or halving the wrong combination to get 17.
Common mistakes
- Reporting the Cougars' score 24 instead of the Panthers' score, or halving the wrong combination to get 17.
- Treating "won by 14" as "scored 14" and answering (B).
Techniques
Set up the equation/formula and compute; no special trick needed