Finding percentage of students with C or C+ grades

[Destrio]

The results of a exam had 15% of students earning atleast a "B", 65% with atleast a "C-", and 45% with less than a "C". What % of the students received a "C" or a "C+"?

The whole less than C and atleast C- thing is throwing me off and I can't seem to wrap my head around it.

Any help would be greatly appreciated.

Thanks

 

[ppyadof]

Try thinking of it like this, if 65% of people got a C or higher, then what percentage got lower than a 'C' (hint: the total of the two must give 100%, since it covers the whole range). Now, using the other value quoted, namely 45%, what is the percentage between the two?

(no. of people with < C) + (no. of people with >= C) = (Total number of people involved)