Aliyah earned a $6,000 bonus from her sales job for exceeding her sales goals. after paying taxes at a 30% rate, she invested the remaining money in two stocks. one stock returned the equivalent of 10% simple interest after 1 yr, and the other returned 4% at the end of 1 yr. if her investments returned $240.00 (excluding commissions) how much did she invest in each stock

Aliyah Earned Bonus of $ 6000 
30% of $ 6000 = $ 1800 
Therefore remaining amount after paying tax = $ (6000 - 1800) 
 = $ 4200
 Hence, She invested total amount of $ 4200 in two stocks say, x and y
 let x - stock that returned 10 % after 1 year
 and y - stock that returned 4 % after 1 year
 x + y = 4200 equation 1
 
 &, (x * 1 * 10)/(100) = 0.1 x
 , (y*1*4)/(100)= 0.04 y
 Now, from given conditions, 
 0.1 x + 0.04 y = 240 equation 2 
 by solving equation 1 and 2 simultaneously we get x and y as,
 x = $ 1200 and
 y = $ 3000