A10 cm3 block of paraffin (a type of wax) weighs 0. 085 n. it is carefully submerged in a container of gasoline. one cm3 of gasoline weighs 0.0069 n.
a. what is the weight of the gasoline displaced by the paraffin?
b. will the block of paraffin sink or float in the gasoline?

You started out by telling us that the block of paraffin has
10 cm³ of volume.  When it's completely submerged, it displaces
10 cm³ of gasoline.  Each cm³ of gasoline weighs 0.0069N, so
the whole 10 of them weigh (10 x 0.0069) = 0.069 N.

We notice that the block of paraffin weighs more than the gasoline
that it displaces.  So there's no doubt about it ... the paraffin sinks
in gasoline.

If you were to drop it into water instead, it wouldn't sink.  Each
cm³ of water weighs 0.0098 N, and 10 of those weigh 0.098N. 
In water, the paraffin would settle down only until it displaced
its own weight ... 0.085 N, about 8.7 cm³ of water ... and then
it would float right there, with about 87% of it under water and
the other 13% of it above the surface.