Answer
93.75 kilometers per hour
Work Step by Step
2.25*100 = 225 ( Distance traveled so far )
350-225=125 ( Distance left to be traveled )
s=d/t=$\frac{125}{1+\frac{20}{60}}=\frac{125}{\frac{4}{3}}=375/4=93.75$ ( Remaining distance left to be traveled )