Question

Xian and his cousin 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 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

5 months

Explanation:

Set this up as an equation, using x to represent the number of months, and solve for x

80 + 8x = 60 + 12x

20 + 8x = 12x

An easy way of solving this is putting both equations, 20 + 8x and 12x, into a graphing calculator and finding where they intersect.

x = 5

In 5 months, Xian and Kai will have the same number of stamps.