Question 548929
Your 75% grade accounts of 90% of your final mark.  
Your final exam (I will call it F) accounts for 10%.  

If you want an A (this is 80% or above):
{{{75*0.9+F*0.1>=80}}}
Now solve for F 
{{{67.5+F*0.1>=80}}}
{{{F*0.1>=80-67.5}}}
{{{F*0.1>=12.5}}}
{{{F>=12.5/0.1}}}
{{{F>=125}}}

Unfortunately, it is not possible to get above 80 as you would need at least 125 on your final exam.  

Now if you want a B(this is 70% or above):
{{{75*0.9+F*0.1>=70}}}
Now solve for F 
{{{67.5+F*0.1>=70}}}
{{{F*0.1>=70-67.5}}}
{{{F*0.1>=2.5}}}
{{{F>=2.5/0.1}}}
{{{F>=25}}}

So this is definately possible! As long as you get over 25%, you will get over 70%.  ((Note: this may change if you have rules about passing your final and if different tests are worth different amounts in the 90%, etc.))