After how many months will Xian and Kai have the same number of stamps? How many stamps will each have?

Question

Xian and his cousin Kai both collect stamps. Xian has 64 stamps, and Kai has 68 stamps. The boys recently joined different stamp-collecting clubs. Xian's club will send him 12 new stamps per month. Kai's club will send him 8 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

Xian has 64 stamps and gets 12 new ones each month --> X = 64 + 12s

Kai has 68 stamps and gets 8 new ones each month --->  K = 68 + 8s

 

To figure out when they will have the same number of stamps, make their equations equal one another...

64 + 12s = 68 + 8s

Solve for s

Plug s back into each equation to check your work and get the answer to the 2nd question above.