Answer:
Jena spends $ 733. 33 on her rent and groceries  altogether per month.
Step-by-step explanation:
Jena's total income in a month= $1600
Here , expenditure on rent = (1/3) of her income
So, now one- third of her income $1600 is  
= 
or,  (1/3) of her salary is  $533. 33
Hence, Jena spends $ 533. 33 on her rent monthly.
Now, her expenditure on groceries = (1/8) of her income
So, now one- eighth of her income $1600 is  
= 
or, (1/8) of her salary is $ 200.
 Jena spends  $ 200. on her groceries  monthly.
So, Total expenditure  = Expenditure on rent + Expenditure on groceries 
= $533. 33 + $200 = $733.33
Hence, Jena spends $ 733. 33 on her rent and groceries  altogether per month.