A two digits number is 21 times the difference and 350% of the product of its digit. Find the quotient of the digit of number​

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

The answer is B. Fabiana has completed the same amount of the course as Samantha because 6/15=8/20. Both fractions reduce to 2/5. Therefore, they are equivalent.