If alvin sold 60% of his baseball cards, gave away 30% of those that were left, and still had 40 baseball cards in his possession, how many baseball cards did alvin have to begin with?

The number of baseball card to begin with is 143

Step-by-step explanation:

Let The number of baseball cards = x

The number of sold baseball card = 60% of x

                                                         = 0.6 x

The number of left baseball card = x - 0.6 x = 0.4 x

The number of card gave away = 30 % of left cards

                                                     = 0.3 × 0.4 x = 0.12 x

The number of card left in his possession = 40

So, 0.6 x + 0.12 x + 40 = x

Or,  40 = x - 0.6 x - 0.12 x

Or,  40 = 0.28 x

∴   x =  =  142.85 ≈ 143

Hence The number of baseball card to begin with is 143  Answer