Here's what I got.
I'm assuming that you're starting with a piece of iron that has a known volume and are interested in finding its mass in pounds.
The thing to keep in mind density is that it can be used as a conversion factor to help you go from mass to volume or vice versa.
Let's say that in your case, you have a piece of iron of volume
As a result, the piece of iron of volume
#V color(red)(cancel(color(black)("cm"^3))) * overbrace("7.9 g"/(1color(red)(cancel(color(black)("cm"^3)))))^(color(blue)("the given density")) = (7.9 * V)" g"#
Now all you have to do is use the given conversion factor
#color(purple)(|bar(ul(color(white)(a/a)color(black)("1 lb " = " 453.6 g")color(white)(a/a)|)))#
to convert the mass from grams to pounds
#(7.9 * V) color(red)(cancel(color(black)("g"))) * "1 lb"/(453.6color(red)(cancel(color(black)("g")))) = (0.0174 * V)" lb"#
As a numerical example, let's say that
#"mass in lb" = 0.0174 * 122 = "2.12 lb"#