After 4 hours, his body will have processed 28% because 7*4 = 28. But, you're trying to find what's left (so, subtract that % from 100)
100%-28% = 72%
Then multiply the percent left by the total number of milligrams of caffeine
130*.72 = 93.6 mg
Answer:
4/5
Step-by-step explanation:
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