1/3x= -7 what would x be?
1/3x=-7
You have to get rid of 1/3 to get x alone, but have to make both sides equal. Divide both sides by 1/3
$${\mathtt{\,-\,}}{\frac{{\mathtt{7}}}{\left({\frac{{\mathtt{1}}}{{\mathtt{3}}}}\right)}} = -{\mathtt{21}}$$
x=-21