Simple probability is desired outcomes divided by total outcomes. 3 red marbles in a bag of 10 is 3/10. Probability as a set is in probability problems.
Count both piles
The denominator is every equally likely result, not only the ones you want. Percents that ask “what percent of” are a different leftover, in what percent of.
The short list is in ACT Math formulas.
The bottom line
Desired over total. Keep the fraction unless they ask for a percent.
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