Uncle Ritchie has some $10 bills in his wallet. He shares all of them equally among his 4 nieces and nephews. Each of the nieces and nephews then donates two $10 bills to charity. They then each have five $10 bills.

How many $10 bills did Uncle Ritchie have in his wallet?

a) write an equation to solve this problem.
b) solve the equation.

a) To solve this problem, we can set up an equation. Let's assume Uncle Ritchie initially had x number of $10 bills in his wallet. After sharing them equally among his 4 nieces and nephews, each of them receives x/4 $10 bills.

Then, each of the nieces and nephews donates two $10 bills to charity, resulting in them having (x/4) - 2 $10 bills each. Since they each end up with five $10 bills, we can write the equation:

(x/4) - 2 = 5

b) Now let's solve the equation to find the value of x.

Adding 2 to both sides of the equation, we have:

(x/4) - 2 + 2 = 5 + 2
(x/4) = 7

To eliminate the fraction, we can multiply both sides of the equation by 4:

4 * (x/4) = 4 * 7
x = 28

Therefore, Uncle Ritchie initially had 28 $10 bills in his wallet.

4 * 7 = x

28 = x