Answer: 28 dollars
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Step-by-step explanation:
G = amount of money George starts with
T = amount of money Tia starts with
Initially the ratio of their money is 9:4 so G/T = 9/4. Solve for G to get G = (9/4)T.
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After George spends 24 dollars he's left with (G-24) dollars. Tia gains 11 dollars so she has (T+11) dollars. They have the same amount of money after these two events occur, so G-24 = T+11.
Plug in G = (9/4)T and solve for T
G-24 = T+11
(9/4)T-24 = T+11 ... replace G with (9/4)T
4*[ (9/4)T-24 ] = 4*[ T+11 ] ... multiply both sides by 4 to clear out fraction
9T - 96 = 4T + 44 ... distribute
9T - 4T = 44 + 96
5T = 140
T = 140/5
T = 28
Tia started off with 28 dollars. We could stop here because your teacher is only asking about Tia's initial amount.
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If you want to find how much George started with, then plug T = 28 into G = (9/4)T to get...
G = (9/4)T
G = (9/4)*28
G = 2.25*28
G = 63
George started off with 63 dollars
The ratio of 63:28 reduces to 9:4 after dividing both parts by the GCF 7. This confirms the first fact we're given.
Notice how 63 drops to 63-24 = 39 after George spends $24. At the same time, Tia's amount increases to 28+11 = 39, which is the same as George's updated amount. Both facts match the description, so we have confirmed the answer.