Your target solution must be
You can use the solution's percent concentration as a conversion factor to calculate the volume of formic acid that must be present in
#755 color(red)(cancel(color(black)("mL solution"))) * overbrace("25.0 mL formic acid"/(100color(red)(cancel(color(black)("mL solution")))))^(color(blue)("= 25.0% v/v")) = color(darkgreen)(ul(color(black)("189 mL formic acid")))#
The answer is rounded to three sig figs.
You can thus say that adding