Janelle is five years younger than Louisa. In three years, Janelle will be half Louisa’s age. If j represents Janelle’s age now and l represents Louisa’s age now, which matrices represent the situation?

“Janelle is five years younger than Louisa” gives j − l = −5. In three years, their ages will be j + 3 and l + 3, so j + 3 = ½(l + 3), which rearranges to j − ½l = −3/2. These equations have coefficients [1, −1] and [1, −½], with constants −5 and −3/2, matching choice C.

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