Answer:
Step-by-step explanation:
Mean: You just add them altogether then divide the sum by how many numbers there are
Median: You put all the numbers from least to greatest then cross one off on the left and do the same on the right and repeat until there is either one or two numbers left if there are two number then you find the mean of those two numbers, but if you only have one number left then that is your answer
Mode: You find which number is the most common for enstance if there are two 3 and one 4 then 3 would be your answer because there are more 3 than 4
Range: You take the highest number and the lowest number of the set and subtract them and then you have your answer
Solution:
we are given that
John is 3 years older than Jim. Jim is 4 years less than half of Dana’s age.
Let the age of Jim be x years then we can say
Age of John
If diana Age is D then

It can be re-wriiten as
Diana age 
Given that their ages add up to 167

Hence jim is 39 nyears old, John is 39+3=42 years old. and Diana is 2*39+8=78+8=86 years old.
The item has 42/140 * 100,or 30% of its initial value. That means that it lost 70% of its value, so 70% is the percent decrease.