If you know that n = 15, substitute 15 for n and solve: n + 3 - 9 15 + 3 - 9 9
15 + n = 24 (subtract 15 from both sides) n = 9
n=6
15 - n when n equals 9 = 6
3n = 15 + 12 = 27, 27/3 = 9 = n
-24
If you know that n = 15, substitute 15 for n and solve: n + 3 - 9 15 + 3 - 9 9
15 + n = 24 (subtract 15 from both sides) n = 9
n=6
15 - n when n equals 9 = 6
9 - 5n + 1 = 15 -5n = 15 - 10 n = -5/5 n = -1
n = 8
3n = 15 + 12 = 27, 27/3 = 9 = n
9
24
n X .15 = 9 9 / .15 = n 9 / .15 = 60
3 + 9 = 12