Answer:  1288- 5t , where t = number of hours Ahmad worked as a tutor this month.
Step-by-step explanation:
Given : The number of hours Ahmad works as a tutor that month = t 
Combined hours of job = 92
 The number of hours Ahmad works as a waiter = 92-t
Amount he got as tutor per hour = $ 9
Amount he will get as tutor  = (Amount he got as tutor per hour ) x (t)
= 9t
Amount he got as waiter per hour = $ 14
Amount he will get as waiter  =  (Amount he got as waiter per hour ) x (92-t)
= 14(92-t)
= 14 (92)-14t  [By distributive property]
= 1288 -14t
Combined  amount he earned this month= Amount he will get as tutor + Amount he got as waiter per hour 
= 9t+  1288 -14t
=1288+9t-14t   [Commutative property]
= 1288- 5t
So , the expression for the combined total dollar amount he earned this month:
 1288- 5t 
where t = number of hours Ahmad worked as a tutor this month.