Hello
If Susan takes 300mg of a drug twice daily

But she was given 75mg tab and takes the drug twice daily
Let's divide her daily dose by the numbers of time she takes it

This implies she takes 150mg in the morning. To find the number of tablets that will amount to 150mg would be

Cross multiply both sides and solve for x

From the calculations above, Susan has to take 2 tablets of her medication in the morning daily.