A builder named Marcus is tiling a conservatory floor using hexagonal tiles arranged in rows. Row 1 has 4 tiles, row 2 has 7 tiles, row 3 has 10 tiles, and the pattern continues, with each row having 3 more tiles than the row before.
(a)Work out how many tiles are needed for row 8.(2)
(b)Marcus has exactly 100 tiles. Working row by row from row 1, work out the greatest number of complete rows he can tile without using more than 100 tiles in total.(3)