23
because
the pattern is
(5 10) ..1.. (15 20) ..2.. (25 30) ..3..
..1... = 3
..2.. = 13
so ..3.. = 23
Solution:
The gas can is filled at the rate of 320 cubic inches per minute.
The can is 10 inches long, 8 inches wide, and 12 inches high.
So volume of the can=10 in*8 in *12 in

Time required to fill the can
Hence Time required to fill the can =3 minutes.
The tank WILL overflow.
60*30*40= 72000cm^3
<em>The max volume the fish tank can hold: 72000cm^3</em>
amount of L * 1000= cm^3
70L * 1000= 70000cm^3
<em>There is already 70000cm^3 of water in the tank</em>
70000cm^3 + 3000cm^3 = 73000cm^3
The tank can only hold 72000cm^3 and the water and rocks are 73000cm^3, so the tank will overflow.