The total amount of fertilizer needed for the rectangular garden is 0.315 kg.
The first step is to determine the area of the garden.
Area of the garden = length x width
=1.2 x 3.5 = 4.2
The second step is to multiply 0.075 by 4.2
0.075 x 4.2 = 0.315 kg
To learn more about multiplication, please check: https://brainly.com/question/3385014