Tanya is printing a report there are 100 sheets of paper on the printer and the number of sheets p left after t minutes of printing is given by the function p(t)=-8t+100
with b-d i already answered a

the domain is a range of values of t (the x variable) that can give real values of y

Since the range ( y variable) is Rp= [0,100] ( round brackets mean excluding the two numbers while square means including ) since there are only 100 sheets of paper, no more no less

so the most t can be is when p=0, when t= 12.5, so domain is Dp= [0,12.5] after 12.5 min, there will be no paper left in the printer, so nothing can be printed

for D, sub t=7, so p(t) is the number of sheets left in the printer, you want to find the no. of sheets deducted so

p(t)=-8(7)+100

=100-15

=85

no. of pages in her report= 100-85= 15