Explanation

From Maryam's purchase:

4C + T = 1800

From Fatima's purchase:

6C + 2T = 3000

We can solve these equations using substitution or elimination. Let's use elimination.

Multiplying the first equation by 2:

8C + 2T = 3600

Now subtracting the second equation from this:

(8C + 2T) - (6C + 2T) = 3600 - 3000

2C = 600

C = 300