How many ml of .048M naoh are required to reach the equivalence point in titrating 28 mL of .018M h2so4

i feel like it should be 10.5 but for some reason my answer key is telling me its 21. please help

Do you have a balanced equation?

2 NaOH + H2SO4 ------> Na2SO4 + 2 HOH (2 H2O)

So you need 2 mole NaOH/Mole H2SO4

Mole sulfuric acid = 0.028 L x 0.018 mole/ L = 0.000504
Mole NaOH = 0.00504 mole H2SO4 x 2mol NaOH/mol H2SO4 = 0.00101 mol NaOH

mL NaOH = 1 L NaOH/0.048 mol NaOH x .00101 mol NaOH = 0.021 liter = 21 mL