Answer:
3
Step-by-step explanation:
The factors of 12a are ...
2×2×3×a
The factors of 27 are ...
3×3×3
The only common factor is 3.
_____
12a -27 = 3(4a -9)
They always say to do the problem in parentheses first
Alright, so we'd use the combinations with repetition formula, so we choose from 4 schools to distribute to and distribute 8 blackboards. It's then
( 8+4-1)!/8!(4-1)!=11!/(3!*8!)=165
For at least one blackboard, we first distribute 1 to each school and then have 4 blackboards left, getting (4+4-1)!/4!(4-1)!=7!/(4!*3!)=35
