0.105 is 0.05 times a number.

Let x represent the unknown number.

Which pair of equations are both true?

​ 0.105x=0.050.105x=0.05 and ​ x=0.00525x=0.00525 ​
0.05x=0.1050.05x=0.105 ​ ​and ​ x=2.1x=2.1 ​
​ 0.05x=0.1050.05x=0.105 ​ and ​ x=0.00525x=0.00525 ​ ​
0.105x=0.050.105x=0.05 and ​ x=2.1x=2.1 ​