Δabc is an equilateral triangle. m∠a = (3x - 12)°. solve for x. a) 14 b) 19 c) 20 d) 24

option (d)

Step-by-step explanation:

An equilateral triangle is a triangle whose all the sides are equal and all the angles are same.

There are three angles in a triangle and the according to the property of the angles of a triangle, the angle sum of a triangle is 180°.

So, in an equilateral triangle, the measure of each angle is 60°.

3x = 60 + 12

3x = 72

x = 24

option (d)

step-by-step explanation:

this can be solved first with pythagorean theorem, which tells us to square both legs of the triangle and sum it. this will be equal to the square of the hypotenuse.

the hypotenuse is the side "opposite" the 90 degree angle, which is x.

so we can write using pythagorean theorem,

simplifying:

to further simplify this radical, we need to use the property  

thus

6 adults and 9 children went.

a + c = 15

12a + 9c = 153

12(6) + 9(9) = 153

72 + 81 = 153