Having received his weekly allowance, John spent 3/5 of his allowance at the arcade. The next day he spent one third of his remaining allowance at the toy store, and then spent his last $0.80 at the candy store. What is John’s weekly allowance?
it's relatively an easy question but what i am interested in is, if this question has to be solve through Plug in or back solving method as the answer choices have fractions......
When you backsolve, just ignore the decimals. For example, 3.20 = 320 cents.
Since after spending 3/5 and 1/3, John spends his last 80 cents, the correct answer must be divisible by 5 and 3. Eliminate C.
Answer choice B: allowance = 300
Spends 3/5, means (2/5)*300 = 120 left.
Spends 1/3, means (2/3)*120 = 80 left.
The correct answer is B.
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