18
Two points (which must lie on a line) and the third point NOT on that line.
Both ends of the line must join together, as in a circle, loop, or a closed figure.
What must be true? In your example, we have 4 intersecting lines. g and b are parallel, and f and h are parallel. g and b are perpendicular to f and h. It might look like tic-tac toe for example
If it is a straight line it must be in the same plane. Otherwise not necessarily.
33 marbles must be in the sixth line
There must be 67 marbles.
36
Well, honey, if the pattern starts with 5 marbles, and each line has a number that's four less than twice the previous line, the sixth line would have 9 marbles. So, you better have 9 marbles lined up and ready to go if you want to keep this pattern going.
33
36
The pattern is 3, 4, 6, 10, 18, 34...So your answer is 34
22 marbles are in the fifth line.
Oh honey, let me break it down for you. If the first line starts with 10 marbles, and each consecutive line has one less marble than the previous line, by the time you get to the seventh line, you'll have 4 marbles. So, grab those 4 marbles and go win that game, darling!
The fifth line will have 19 marbles. 4 5 7 11 19
17
I'm coming up with 63. <------Answer is completely wrong! The actual answer is: 1. Just minus one every time you go down a row.