How would i be able to find my answer to this problem?

Apositive number a or the same number a increased by 50% and then decreased by 50% of the result?

Kayaks rent for $35 per day. which expression can you use to find the cost in dollars of renting 3 kayaks for a day?

36x2 + 49y2 = 1,764 the foci are located at: (-√13, 0) and (√13,0) (0, -√13) and (0,√13) (-1, 0) and (1, 0)edit: the answer is (- the square root of 13, 0) and (the square root of 13, 0)