Aina, kareem, and david have a total of $92 in their wallets. kareem has $7 less than raina. david has 3 times what kareem has. how much do they have in their wallets?

Kareem has $17, David has $51, Raina has $24 



Step 1:
Solve this by using a system of equations. Start by changing what you're given from words into equations. Put variables in for the peoples' names. Let's say Raina = R, Kareem = K, and David = D. You will have 3 equations:
1) Raina, Kareem, and David have a total of $92 in their wallets.
R + K + D (sum of all three) = 92 (total)

2) Kareem has $7 less than Raina
K = R - 7 (seven less than Raina)

3) David has 3 times what Kareem has.
D = 3K (three times Kareem)



Step 2:
You can solve for the values of R, K, and D using substitution. Let's put the first equation, R + K + D = 92, all in terms of one variable, so we can solve for that variable. Since both equations 2 and 3 have K in relation to one of the other variables, I will be putting equation 1 in terms of K! Do this by substitution some equation of K in for variables R and D in the first equation.

From equation 2, we know that K = R - 7. Add 7 to both sides, making R = K + 7. 
From equation 3, we know that D = 3K. This is already in perfect form to substitute. 

Now substitute both R = K + 7 and D = 3K into the first equation. Simplify and solve for K:
R + K + D = 92
(K + 7) + K + (3K) = 92
5K + 7 = 92
5K = 85
K = 17

Kareem has $17 in his wallet.



Step 3: 
Now that you know K = 17, plug that into equation 3, D = 3K, and solve for how much David has:
D = 3K
D = 3(17)
D = 51

David has $51 in his wallet.



Step 4: 
Finally, plug K = 17 into equation 2, K = R - 7, to find how much Raina has: 
K = R - 7 
17 = R - 7
R = 24

Raina has $24 in her wallet.