Johanna used tiles to build a rectangular array with an area of 54. list all the possible dimension of the arrey

Really this is an exercise in factorization. First find all the factors of 54: 1, 2, 3, 6, 9, 18, 27, 54

Then use each of those in a multiplication to get 54:

1*54

2*27

3*18

6x9

That's it. 4 possibilities.