2expressions where the solution is 19

Pyramid shown has a square base that is 18 inches on each side has a surface area of 164 square inches what is the slant height

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18

The first term of a sequence is -12. the recursive formula for the sequence is an = an-1 + 9. what are the next 3 terms in the sequence? a) -3, -15, -27 b) -3, 6, 15 c) -3, -6, -3 d) -3, -6, 3