The half-life of a radioactive isotope is 10 years. about how long would it take 5 grams of the isotope to decay until there were only 2.5 grams left?

a. 10 years
b. 20 years
c. 30 years
d. 40 years

Option A. 10 years

Step-by-step explanation:

we know that

Half-life is the amount of time required for a quantity to fall to half its value as measured at the beginning of the time period.

In this problem   of a radioactive isotope is 10 years, which means that after 10 years half of the sample would have decayed and half would be left as it is.

After 10 years ( first half life) 5/2 = 2.5 g decays and 2.5 g remains left

fa tha first one you gonna add y to both sides

it look like this

x-y+y=6+y

x=y+6

therefore your answer is

x =y+6

fa tha second one

you gonna flip tha equation

it gonna look like x-4y=y

then add 4 to both sides

it gonna look like tha

x-4 +4 =y +4

so therefore tha answer is x=y+4

step-by-step explanation:

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x