10% of 3000 is 300.
Theirs monthly expense on clothes is $300.
Lin's number is 15 and Jen's number is 105.
15 is a two digit number and if we multiply it with 7, we get the answer 105.
15 x 7 = 105
And if we put 0 between the Lin's number that is 15, we will get 105
Thus, 15 and 105 are two numbers.