If The Standard Deviation Of The Distribution Of The Difference Between Means Is .76, What Is T Score?

Standard Deviation Of The Distribution Of The Difference Between Means is known as standard error
 
t-score = (mean1-mean2)/ standard error

Here
mean 1 = 55
mean 2 = 51
Standard error=0.76  (square root of (6.5/15 + 4.5/23))
 
T-score = (55-51)/0.76
=4/0.76
 
T-score =5.263 >>> answer