The answer is negative four. subtract six from both sides and you get -20=5x then you would divide both sides by 5 and get -4
First differences are all 7.3. You don't need a graph to know that is a linear function.
You can write the problem with a division box, move the divisor decimal point the amount of spaces that it would take to make the number whole. Move the decimal if the dividend the same amount of spaces as the divisor. Move the decimal point directly up above the division bar, divide, check your work