Answer
210 pink tiles, 190 blue tiles.
Work Step by Step
Pink tiles:
Bottom row: 20 tiles, and one less for each following row.
20+19+18+...+2+1= sum of arithmetic sequence, $a_{1}=20,d=-1,n=20.$
$S_{n}=\displaystyle \frac{n}{2}\left(a_{1}+a_{n}\right)=10(20+1)=210$
Blue tiles:
19 in the bottom row, 1 in the top row:
19+18+...+2+1= sum of arithmetic sequence, $a_{1}=19,d=-1,n=19.$
$S_{n}=\displaystyle \frac{n}{2}\left(a_{1}+a_{n}\right)=\frac{19}{2}(19+1)=19(10)=190$
