John took all his money from his savings account. he spent $72 on a radio and two thirds of what was left on presents for his friends. john then put five twelfths of his remaining money into a checking account and donated the $140 that was left to charity. how much money did john originally have in his savings account

Let us assume amount of money John originally have in his savings account = $x

Money spent on a radio = $72.

Reamining money = x-72.

Money spent on presents for his friends = Two third of remaining money = 2/3 (x-72).

(Because 1 - 2/3  = 1/1 - 2/3  = 1/3)

Reamining money = 1/3 (x-72).

Five twelfths of his remaining money into a checking account = 5/12 * 1/3 (x-72).

( becasue 1 - 5/12 = 1/1 -5/12 = 7/12)

Reamining money = 7/12 * 1/3*(x - 72).

Final remaining money = 7/12 * 1/3*(x - 72) and that is equal to the money donated to charity.

We can setup an equation now.

7/12 * 1/3*(x - 72) = 140.

7/36 (x-72) = 140.

Multiplying both sides by 36.

36 * 7/36 (x-72) = 140 * 36

7(x-72) = 5040.

Dividing both sides by 7, we get

7(x-72)/7 = 5040/7

x-72 = 720

Adding 72 on both side, we get

x-72+72 = 720+72.

x= 792.

Therefore, john originally have $792 in his savings account.

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)

1 + (6 / x - 1)

step-by-step explanation:

divide using polynomial division.