A solution is made by dissolving 29 g of sodium chloride to a final volume of 202 mL solution. What is the mass/volume % of the solute?

A solution's mass by volume percent concentration, #"% m/v"#, is simply the number of grams of solute present in #"100 mL"# of solution.

This means that in order to find your solution's mass by volume percent concentration, you need to figure out how many grams of solute, which in your case is sodium chloride, #"NaCl"#, you get in #"100 mL"# of solution.

At that point, you can tag along a #%# sign to the value to get the answer.

Notice that the problem tells you that your solution contains #"29 g"# of solute in #"202 mL"# of solution. This know composition of the solution can be used to figure out how many grams of sodium chloride you'd get in a little under half that volume

#100 color(red)(cancel(color(black)("mL solution"))) * "29 g NaCl"/(202color(red)(cancel(color(black)("mL solution")))) = "14.356 g NaCl"#

Since this is how many grams of solute you get in #"100 mL"# of solution, you can add a #%# sign to that value and say that the mass by volume percent concentration is equal to

#"% m/v NaCl" = color(green)(|bar(ul(color(white)(a/a)color(black)(14.3%)color(white)(a/a)|)))#

I'll leave the answer rounded to three sig figs, but keep in mind that you have two sig figs for the mass of sodium chloride.