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?

Janell is five years younger thant Louisa => J = L - 5

In three years, Janelle will be half Louisas's age => J + 3 = (L + 3) / 2

=> J - L = 5

and

2J + 6 = L + 3 => 2J - L = 3 - 6

=> 2J - L = - 3

So, the equations are:

J - L = 5

2 J - L = - 3

Which in matrix form is:


|1   -2 |     | J |       |  5  |
|         |     |    |  =   |      |
|2   -1 |     | L |       | -3  |