Answer:
do distributive property on both, so multiply 6•x and 6•-4. then multiply 7•x and 7•3.
so it'll basically be 6x - 24 = 7x + 21.
then add 24 to both sides so: 6x - 24 + 24 = 7x + 21 + 24. since -24+24=0 it'll be 6x = 7x + 21 + 24.
then add 21 + 24 and that will be 45.
so 6x = 7x + 45
then subtract 7x from both sides 6x - 7x = 7x + 45 - 7x
that'll be -x = 7x + 45 - 7x
combine like terms (7x - 7x) = 0
so -x = 45
and since x can't be negative, do the opposite signs
so instead of -x = 45, make it x = -45
Hope it helped! (sorry that's its very long just wanted to show u the steps just in case)