I tried to answer this question and kept getting it wrong. Can somebody help me?

Question

Xian and Kai both collect stamps. Xian has 60 stamps and Kai has 80 stamps. The boys recently joined different stamp-collecting clubs. Xian’s club will send him 20 new stamps per month. Kai’s club will send him 16 new stamps per month. After how many months will Xian and Kai have the same number of stamps? How many stamps will each have?

Answer 1

Let X be the number of stamps Xian has, K be the number of stamps Kai has, and t be the number of months that elapse.

We can describe the number of stamps each has after t months with a function

X(t) = 60 + 20t

K(t) = 80 + 16t

So when t = 0 (no months elapse), Xian has 60 stamps and Kai has 80 stamps

For each new month, Xian gets 20 more stamps and Kai gets 16, which is why we have 20t and 16t in the equations.

Now we have to find out how many months have passed until X(t) = K(t). To find that out we'll set the equations equal to each other:

X(t) = K(t)

60 + 20t = 80 + 16t

4t = 20

t = 5

So after 5 months they'll have an equal number of stamps. To find out how many, substitute 5 for t in Xian's or Kai's equation and solve

Let me know if you have any quesitons

Answer 2

x = number of months

xian total stamps = 60 + 20x

kai total stamps = 80 + 16x

they will be equal when: 60 + 20x = 80 + 16x

4x = 20

x=5 months