A piece of glass has two radii. The left side has a radius of 2 cm and the right has a radii of 4 cm. The two are seperated by 8 cm. There is a point object 1 cm left of the glass, find the position of the image. I need to use the equation n2-n1/R = n1/do + n2/di, i need to use it twice, once for each radius, and one time it would be negative (the radius). 1.5-1 / .02 = 1/.01 + 1.5/di Solved it and got di=2 cm 1.5-1/-.04 = 1/.09 + 1.5/di Solved it got di to be -12 cm. Combined the two to get -12 + 2 = -10 cm..10 cm behind the piece of glass...does this seem right?