12y - 9 = 21 : Add 9 to both sides
12y = 30 : Divide both sides by 12
y = 30/12 = 2.5 or 21/2.
21
12
-16
n + 13 = 21. n = 21 - 13
3, 7, 21. 3x7 is the only equation that equals 21, and so these are the only factors of 21.
32
9+12
It is an equation and the value of x is 7
120 - 90x = 210
21
5
If the equation is 7x - 3y = 21 then (3, 0) and (0, -7).