which term of sequence,24,23 1/4,22 1/2,21 3/4 is the first negative term?

The given sequence is an A.P. with forst term as 24,

 common difference = diff bet consecutive terms= 23.25-24=22.5-23.25=......= -0.75

so we ahve

 a=24, d=-0.75

If zero is one of the terms of this series then the first negative term will come immediately after zero. So let's see at what place does zero come in this series assuming that it's a part of this series.

let zero come as the nth term..

a+(n-1)d=0

24+(n-1)(0.75)=0

solving we get,

 n=33

Since 0 is the 33rd term, so the next term willbe thefirst negative term, i.e. the 34th term will be thefirst negative term of the A.P.