You find a rock containing a mixture of element and lead. you determine that 20% of the orignial element remain; the other 80% decayed into leads. how old is the rock?

hdjd

step-by-step explanation:

b. 1.25 hr

step-by-step explanation:

if you have a constant speed of 60 mph, then you have a ratio between 60 mi. to 1 hr. dividing both sides by 60 we get the ratio

1 mi. to

then mult. both sides by 75 we get the ratio

75 mi. to

simplifying we get

75 mi. to

or 1.25 hr.

what is the answer to this

b. hoped i'm right lol

step-by-step explanation: