-20=-4x-6x

 -4x-6x equals -10x, so tou get -20=-10x, devide both sides by -10, and you end up with x =2

make both sides even

20=(4*6)x

20/24=24x/24

.83333333....=x

at least i think it does, you may want to check my work

Thanks for 'having a go' unknown - I like to see that.  

But, the second answer is correct.