AP Chemistry junior summer assignment. It’s killing me.
3 Answers

Look up SI conversions
1 m^3 = 1000 litres
1 kg = 1000 gram
always write the conversion out in full; no shortcuts.
(1.55kg/m^3)x(1000g/kg)x(1m^3/1000L)
=1.55x (1000xkgxg/kg) x (m^3/(m^3x1000x L))
Then cancel out the units
=1.55 g/L

Start with what you know
1 kg = 1000 g
1 m = 100 cm
Therefore 1 m^3 = 100x100x100 cm^3
you have 1550 g per 1000000 cm^3
1 liter = 1000 cm^3
1000000 cm^3 / 1000 cm^3/liter = 1000 liters
1550 g / 1000 liters
1.550 g/L

1kg = 1,000g.
and; 1 L = 1,000mL;
also, 1mÂ³ = 1,000,000mL / 1,000mL/L. = 1,000L.
1.55kg/mÂ³ x 1,000g/kg = 1,550g/mÂ³. = 1,550g / 1,000L.
1,550g / 1,000L = 1.55g/L.