MathDB
x+19y = 0 mod 23 and x+y < 69

Source: 0

April 28, 2009
modular arithmetic

Problem Statement

x \plus{} 19y \equiv 0 \pmod {23} and x \plus{} y < 69. How many pairs of (x,y) (x,y) are there in positive integers?
<spanclass=latexbold>(A)</span> 100<spanclass=latexbold>(B)</span> 102<spanclass=latexbold>(C)</span> 105<spanclass=latexbold>(D)</span> 109<spanclass=latexbold>(E)</span> None<span class='latex-bold'>(A)</span>\ 100 \qquad<span class='latex-bold'>(B)</span>\ 102 \qquad<span class='latex-bold'>(C)</span>\ 105 \qquad<span class='latex-bold'>(D)</span>\ 109 \qquad<span class='latex-bold'>(E)</span>\ \text{None}