No sorry I wrote:
Volume = mass/density
In this case it was:
Mass = Density/Volume
You have to take the volume of water and substract it from the final volume from when you added the lead:
42.6mL - 31.0mL = 11.6mL
11.6mL is the volume of the lead
the Density of lead is 11.34 g*cm-³
remember: cm-³ = mL so just change it to 11.34 g*mL so mL gets canceled.
Now you:
Mass = Density/Volume
Mass = 11.34 g*mL/11.6mL
you divide 11.34 into 11.6 and the mL get cancelled
you get:
Mass = 0.977586
with scientific notation
Mass = 9.8 x 10^-1g