Need to know: Ray Villalobos course - Layouts with Columns and Flexbox

box -1 flex row
box -2
box -3
box 1-1 flex row
box 2-1
box 3-1
box 4 not flex row
box 5
box 6
box 7 not flex row
box 8
box 9
box 10 not flex row
box 11
box 12
box 13 not flex row
box 14
box 15