The first triangle is equilateral.
This is shown because all of the angles are 60°. Another way to know this is because of the lines sticking out from all three sides, these lines indicate that the sides of the triangle are of equal length. Therefore, it is equilateral.
The second triangle is a right triangle. The bottom left angle has a square in it, this indicates a 90° angle. Therefore, it is a right triangle.
The third triangle is scalene. None of the sides are the same length, indicating a scalene triangle.
For question 11, x = 40
180 = x + 2x + (x + 20)
180 = 4x + 20
160 = 4x
40 = x
For 12, x = 12
90 = 3x + 10 + 3x + 8
90 = 6x + 18
72 = 6x
12 = x
The fourth triangle is acute because none of its angles are equal to or above 90°
The fifth triangle is equilateral because all of the angles are 60°
The sixth triangle is a right triangle cause it has the 90° square
For 7, x = 93
180 = x + 52 + 35
180 = x + 87
93 = x
For 8, x = 75
180 = 2x + 30
150 = 2x
75 = x
For 9, x = 23
90 = x + 2x + 21
90 = 3x + 21
69 = 3x
23 = x
For 10, x = 51
3x - 22 = 180 - z
80 + x + z = 180
3x + z - 22 = 180
80 + x + z = 180
3x + z = 202
x + z = 100
2x = 102
X = 51
Hope this helps!