When 21 is divided by j, the remainder is 3. if j is less than 9, what is the remainder when 30 is divided by j? explain your answer?

21/j = i + 3/j; where i is an integer

21/j = ij/j + 3/j

21 = ij + 3

18 = ij

Since j is less than 9, the only options for i are 3, 6, & 9. 3 can be eliminated because it is evenly divided into 21 (therefore no remainder of 3). So the only options for j are 6 and 3.

30/6 = 5 with no remainder 30/3 = 10 with no remainder

Answer: remainder is 0