Question 58276
The letters of word ALGEBRA 
a- How many diffrent ways the letters can be arranged in a row ?
7!/2!=2520
b- In how many ways of these arrangments the two A's are together?
Harness the A's together then you have 6!=720 arrangements.
c- In how many ways of these arrangments the two A's are not together?
2520-720=1800
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Cheers,
Stan H.