Unit rate
A rate is a unit rate when the denominator is 1. Then, in each part we must simplify the fractions so we find them as a unit rate:
3 Tbsp/2 tsp = 1.5 Tbsp / tsp
135 piches/45 strikes = 3 pitches / strike
128 miles/4 hours = 32 miles/hour
2250 pencils/18 boxes = 125 pencils/box