The number is 63, so the quotient is 2.
Two digit numbers divisible by 21:
21, 42, 63, 84
21: 2-1 = 1 * 3.5 = 3.5
3.5*2*1 = 7 but 7 does not equal 21
42: 4-2 = 2 * 3.5 = 7
3.5*4*2 = 28 does not equal 42
63: 6-3 = 3*3.5 = 13.5
3.5*6*3 = 63 :)
Check:
21(6-3)=21(3)= 63 :)
3.5(6)(3) = 21(3) = 63 :)
63: 6/3 = 2
