Well we already know that the 36:100 is correct because it is the starting amount, to check the 18:50 50 is half of the 100 insects so you would divide 36 by 2 which gives you half of 36 which is 18 so we can check off 18:50 as correct. Idk about the final one but the other two are correct.
A horizontal shift to the right by "h" units is achieved by replacing x with (x-h). The shift we want is to the left by 2 units, so h = -2, and we have ...