Answer:
Step-by-step explanation:
As an example, iodine-131 is a radioisotope with a half-life of 8 days. It decays by beta particle emission into xenon-131. After eight days have passed, half of the atoms of any sample of iodine-131 will have decayed, and the sample will now be 50% iodine-131 and 50% xenon-131.
50 grams to 25 grams is one half-life. 25 grams to 12.5 grams is another half-life. So, for 50 grams to decay to 12.5 grams, two half-lives, which would take 36 days total, would need to pass. This means each half-life for element X is 18 days.
Answer:
Real word Problem:- Jean is working in a pizza shop. She has 60 kg of flour. She has used one-fifth of it for making pizzas. How much flour she used for making pizzas?
Solution:- Quantity of flour she has= 60 kg
The quantity she used in making pizzas=
hence, she used 12 kg of flour for making pizzas.
Here the multiplication of a fraction and a whole number 
and its answer is between 10 and 15, since 10<12<15.
X=the number we have to find.
This expression "2(x+9)" is when the sum of a number and nine is doubled.
If the result is seven less than the number, we will have: x-7
We can suggest the following equation:
2(x+9)=(x-7)
2x+18=x-7
2x-x=-7-18
x=-25
answer: the number would be: -25.
432,288 miles.
Google something like this lol
Distance=speed times time
distance=30mi
speed=15mph
t=t
so
30=15 times t
divide both sides by 15
2=t
2 hours
