If a plastic cup cost 800 naira and half a dozen of it cost 4200 naira find the discount on half a dozen.​

x=-2

step-by-step explanation:

i began by flipping the problem to give me x= on the left (keeps it clearer for me).   so my problem simply became 10x-3=4x-6.  

1)   subtract 4x from the right side, which equals 0.   you do the same to the left of the equal as the right; therefore, subtract 4x from 10x, leaving 6x on the left.

              10x-3=4x-6   :   4x-4x on the right leaves only the -6        

2)             6x-3= 0-6 :    

                6x+3=   -6

3) divide