Can anybody me with the questions that are incompleted

8) 2 x 3² x 5
= 2 x 9 x 5
=90

9) you just put P into the expression so the blanks are
2(13-2) = 2 x 11 = 22
2(13-3) = 2 x 10 = 20
2(13-4) = 2 x 9 = 18

10) this is the same so
3x4 + 2 = 12 + 2 = 14
3x6 + 3 = 18 + 3 = 21
3x8 + 4 = 24 + 4 = 28

11)this is also the same so
2²+1 = 4+1 = 5
6²+2 = 36+2 = 38
8²+4 = 64+4 = 68

12) substitute 12 in for c so
12 + 0.08x12 = $12.96

13) substitute 300 in for k
1.15x 300 = 345 miles per hour

14) substitute 8 in for n
6.5x8 + 3 = $55