A simple 9th Grade Math Question. I need help. Any help will be appreciated. The soldiers at the parade lined up in a rectangle with 10 rows and 5 columns. You
need to choose three soldiers so that neither two of them stand in the same row or
in the same column. How many different combinations of such choices are there?

P. S. 19 points for this! Please do answer quick!

(01.02 lc) angle abc has point e on ray ba and point d on ray bc. points e and d are equidistant from point b. to bisect angle abc, which of the following needs to be identified for the construction? the distance between points e and d the point in the angle that is equidistant from points e and d the endpoint of rays ba and bc the point outside of the angle that is equidistant from points e and d

Parabolas y=−2x^2 and y=2x^2 +k intersect at points a and b that are in the third and the fourth quadrants respectively. find k if length of the segment ab is 5.

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?