as i am reading the question, I notice they give two concentrations (M), one volume (L), and they are asking for another volume. this is a hint that you need to use the following formula
C1V1 = C2V2 (note: C stands for concentration)
C1= 2.9 M
V1= ?
C2= 1.1 M
V2= 2.3 L
now let's plug in the numbers
( 2.9 x V1)= (1.1 X 2.3)
V1= 0.87 Liters
