By the values given in the table, for base length and height of the parallelograms, you can notice that base length increases 1 units, so you have 1,2,3,4,5. For height you can notice that while base length increase 1 unit, height decreases by a factor of 1/x, just as follow:
1 - 48
2 - 24
3 - 16
4 - 12
5 - 8
The relation between base length and height is:
f(x) = 48/x
where f(x) is the height and x is the base length. In fact, you have:
f(1) = 48/1 = 48
f(2) = 48/2 = 24
f(3) = 48/3 = 16
f(4) = 48/4 = 12