Question 669329
{{{10!/ 7!3!
=(10*9*8*7*6*5*4*3*2*1)/((7*6*5*4*3*2*1)(3*2*1))=(10*9*8*cross(7)*cross(6)*cross(5)*cross(4)*cross(3)*cross(2)*cross(1))/((cross(7)*cross(6)*cross(5)*cross(4)*3*2*1)(cross(3)*cross(2)*cross(1)))=(10*cross(9)3*cross(8)4)/(cross(3)*cross(2)*1)=(10*3*4)/1=120}}}