Assuming that pamoic acid is that soluble, here's how you would do the calculation.
Pamoic acid is a dibasic acid with the formula "C"_23"H"_16"O"_6C23H16O6.
We can write the formula as "H"_2"C"_23"H"_14"O"_6H2C23H14O6.
Then the equation for the neutralization is
M_text(r):color(white)(m)338.375color(white)(mmm)39.997Mr:m338.375mmm39.997
color(white)(mm)"H"_2"C"_23"H"_14"O"_6 + "2NaOH" → "Na"_2"C"_23"H"_14"O"_6 + 2"H"_2"O"mmH2C23H14O6+2NaOH→Na2C23H14O6+2H2O
color(white)(mmmml)"H"_2"A"color(white)(mll) + "2NaOH" → color(white)(mm)"Na"_2"A" color(white)(mll)+ 2"H"_2"O"mmmmlH2Amll+2NaOH→mmNa2Amll+2H2O
Step 1. Calculate the moles of "H"_2"A"H2A
"Moles of H"_2"A" = 0.500 color(red)(cancel(color(black)("L H"_2"A"))) × ("1 mol H"_2"A")/(1 color(red)(cancel(color(black)("L H"_2"A")))) = "0.50 mol H"_2"A"
Step 2. Calculate the moles of "NaOH"
"Moles of NaOH" = 0.50 color(red)(cancel(color(black)("mol H"_2"A"))) × "2 mol NaOH"/(1 color(red)(cancel(color(black)("mol H"_2"A")))) = "1.0 mol NaOH"
Step 3. Calculate the mass of "NaOH"
"Mass of NaOH" = 1.0 color(red)(cancel(color(black)("mol NaOH"))) × "39.997 g NaOH"/(1 color(red)(cancel(color(black)("mol NaOH")))) = "40 g NaOH"