Question 51848
First assign the variable n.
number of mg of vitamin c in an apple:n
number of mg of vitamin c in an orange is 10 times the apple(the apple has n):10n  (10n =10 times n)
They also tell us that the orange has 80 mg of vitamin c:80
Notice that the vitamin c in an orange is 10n and 80.  They are equal to each other.
10n=80
10n/10=80/10  divide both sides by 10
n=8           simplify
This means that the apple has 8 mg of vitamin C.  Don't forget that when you're dealing with word problems you need to make sure that you answer the question with the appropriate units.