Answer:
11
Step-by-step explanation:
You have to make it into an linear equation.
We're going to put n instead of number.
9 lots of n = 9n.
9n + 30 = 140 - n.
-30 on both sides.
9n = 110 - n.
+n on both sides.
10n = 110.
Divide by 10 on both sides.
Therefore, n = 11.
Hope this helps :)
