Respuesta :

a) x=7, you divide both sides by -3 to get x by itself.

b) x=4, you add 7x to both sides to get all the x on one side, you then add 20 to both sides to get all constants on both sides. lastly, you divide by 9 to get x by itself.
a) -3x=-21
x=-21/-3
x=7

b) -7x+16=2x-20
-7x-2x=-20-16
-9x=-36
x=-36/-9
x=4