Calculate [OH^ - ] for strong base solution: 14.0 mL of 1.20×10−2 M Ca(OH)_2 diluted to 430.0 mL.

you are diluting it 430/14 times, or about 31 times.

Molarity= appx 1/30 original. Now the molarity of the OH is twice that (notice the formula for Cacium hydroxide.