Answer:
$18
Step-by-step explanation:
we proceed by first solving for the unit cost of a sheet
then calculate the cost for any number of sheet
We are told that a builder could buy 6 sheets for the cost of $9
this means that one sheet would cost 9/6= $1.5
Now the builder buys 12 sheets
therefore the cost of 12 sheets will be
12*1.5= $18
