Math..please help!
posted by jan .
During a recent telethon, people pledged $25 or $50. Twice as many people pledged $25 as $50. Altogether, $18,000 was pledged. How many people pledged $25?

N*25+ N/2 *50=18000
solve for N. 
360 people pledged $259,000
180 people pledged $50  9,000