I don't see any problem with this task to be not a GMAT question. I think it is more than possible to solve it in 2 minutes. I don't know any formula for this problem, just the logic. If we talk about procedure I can only suggest that you should go from the smallest triangles to the largest. I attach similar problem

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**File comment:** Just similar problem

howmanysquares.png [ 176.67 KiB | Viewed 831 times ]

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I'm happy, if I make math for you slightly clearer

And yes, I like kudos:)