1998 AJHSME Problems/Problem 10

Problem 10

Each of the letters $\text{W}$ , $\text{X}$ , $\text{Y}$ , and $\text{Z}$ represents a different integer in the set $\{ 1,2,3,4\}$ , but not necessarily in that order. If $\dfrac{\text{W}}{\text{X}} - \dfrac{\text{Y}}{\text{Z}}=1$ , then the sum of $\text{W}$ and $\text{Y}$ is

$\text{(A)}\ 3 \qquad \text{(B)}\ 4 \qquad \text{(C)}\ 5 \qquad \text{(D)}\ 6 \qquad \text{(E)}\ 7$

Solution

There are different ways to approach this problem, and I'll start with the different factor of the numbers of the set $\{ 1,2,3,4\}$ .

$1$ has factor $1$ .

$2$ has factors $1$ and $2$

$3$ has factors $1$ and $3$

$4$ has factors $1$ , $2$ , and $4$ .

From here, we note that even though all numbers have the factor $1$ , only $4$ has another factor other than $1$ in the set (ie. $2$ )

We could therefore have one fraction be $\frac{4}{2}$ and another $\frac{3}{1}$ .

The sum of the numerators is $4+3=7=\boxed{E}$

1998 AJHSME (Problems • Answer Key • Resources)
Preceded by 1997 AJHSME	Followed by 1999 AMC 8
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1998 AJHSME Problems/Problem 10

Problem 10

Solution

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