Answer:
n = 25/2, or n = 12 1/2
Explanation:
It's essential that you use parentheses here to show how your numerals are grouped. I have made some assumptions here, and believe you meant:
(1 1/2)(n - 4 1/2) = 12.
First, convert 1 1/2 and 4 1/2 into improper fractions:
(3/2)(n - 9/2) = 12
Multiplying both sides by (2/3) eliminates the fractional coefficient (3/2):
n - 9/2 = (2/3)(12), or n - 9/2 = 8.
Again, eliminate the fraction by multiplying all terms by 2:
2n - 9 = 16
Then 2n = 25, and n = 25/2, or n = 12 1/2