How many mL of 4.50 M NaOH must be diluted to produce 160.0 mL of 2.50 M NaOH?

Answer 1

2.5/4.5 = 5/9
You want 5/9 the molarity, so you need 9/5 the volume

9/5 * 160 = 288

288-160 = 128 ml of H2O