Write equation and solve.

Half of your baseball card collection got wet and was ruined. You bought 15 cards to replace some that were lost. How many did you begin with if you now have 38 cards

(38 - 15) * 2 = c

c = original cards.

38 - 15 = 23

23 * 2 = 46

You started with 46 cards.

38 - 15 represents subtracting the cards you bought from the half of your original cards.

The * 2 represents multiplying the number of cards you had (without the new ones you bought) being multiplied by 2 (because you lost half of them).

46

Take 15 away from 38

=23

Then you double that

=46