Calculating Donation Amounts

During a fundraising campaign, a non-profit organization received donations from three different sources: $A$, $B$, and $C$. The amount received from source $A$ is represented as 50% of the total donations. The amount received from source $B$ is $250$ less than the amount received from source $C$. If the total donations amounted to $7000$, what was the amount received from source $B$?