halo Guys, I need help in solving the following simultaneous equations manually in an easy way as I am in grade 10 and can't use GDC.

what I have tried :
1. tried subtracting them, but I ended up with big equations to the power of 6
2. tried making c or K as a subject for substitution but ended up like no 1
3. I tried looking for cancellation since I noticed some parts of the equations are exactly the same but still end up with difficult equations.
thanks for your help!

what I have tried :
1. tried subtracting them, but I ended up with big equations to the power of 6
2. tried making c or K as a subject for substitution but ended up like no 1
3. I tried looking for cancellation since I noticed some parts of the equations are exactly the same but still end up with difficult equations.
thanks for your help!