You started with 40 baseball cards.
To find the answer to this problem, you need to work backward. 39(your current amount) - 19(the amount you added) = 20. And if 20 is only half of what you started with, you'd need to multiply 20 by 2, which is 40. So you started with 40.
<span>$2376
880+880+616(70% of 880)= $2376</span><span>
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If you find a wrong thing on answer respond me
A= 50.27 cm^2 :) hopefully this is right