What is the perimeter of the isosceles triangle shown below?
A. 24 units
B. 18 units
C. 21 units
D. 12 units

B. 18 units

Step-by-step explanation:

The triangle can be divided into two right angle triangles whose height is 3 units and the upper width is 4 units.

Using pythagora's theorem to find the slant side (hypotenus) of each right angle triangle

y^2 = 4^2 + 3^2 = 25

y = 5 units.

The total width of the upper side of the triangle is 8 units,

The perimeter is the addition of all the sides of the triangle which is;

8 units + 5 units + 5 units = 18 units

See image below

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

-80x+28y-56 is the correct answer