Arectangular gasoline tank can hold 49.0 kg of gasoline when full. what is the depth of the tank (in m) if it is 0.400 m wide by 0.900 m long?

We know that

ρ = density of gasoline = 737 kg/m³ (at T = 60°F = 15.6°C)
ρ = m/V
ρV = m
V = m/ρ
V = 49.0 kg / 737 kg/m³
V = 0.066 m³ 

[volume of the tank]=L*W*H> H=volume/[L*W]> H=0.066/(0.9*0.4)
H=0.1833 m

the answer is
the depth of the tank is 0.18 m