If c^2>a^2+b^2, then the triangle is obtuse. Since 24^2 + 7^2 is 625, and the square root of 625 is 25, that means 26>25. This proves that the triangle is obtuse.
i dont know how your teacher teaches it but in the first question take away the y after the 25. number 2 the start equation would be 55=2x+25 then you would subtract 25 from each side to get 30=2x, the divide by to to get x=15 or she made 15 calls. number 3 is correct.