If Biftu gives me a penny, I will have twice as many pennies as he has. If I give Biftu a penny, he and I will have the same number of pennies. How many pennies do I currently have?

qwertyuiopasdfghjkl Aug 18, 2020

#1**+1 **

You have 7 to start with Bitfu has 5

x = yours y = b's

x+1 = 2(y-1) and

x-1 = y+1 these are given in the description

re-arrange the second equation x = y+2 sub this into the first equation

y+2 +1 = 2y-2

y + 3 = 2y-2

y = 5 then x = y+2 = 7

ElectricPavlov Aug 18, 2020

edited by
Guest
Aug 18, 2020