Answer:
D
Step-by-step explanation:
Subtract 60 from 80 to get 20, and divide 20 by 80 to get 1/4, which can be converted to 25%.
16x
Both of these expressions are similar expressions, therefore you can simply add the number in front of the 'x'
6 + 10 = 16
Therefore, 6x + 10x = 16x
The correct option is B. Distributive property
Given,
On solving the above equation,
multiplying both sides by 3 we, get

now subtracting 21 from both the sides,

dividing both the sides by 2 we get,

Since in the above steps we follow all the giving property except the distributive property.
Hence the correct option is B. Distributive property.
For more details follow the link:
brainly.com/question/13130806
Surface area of the pyramid= 4*(area of the triangle) + area of the square
Area of the triangle = (1/2)*base*height=(1/2)*5*5= 25/2 in²
Area of the square = 5*5 =25 in²
Surface area of the pyramid = 4*(25/2) + 25=2*25 + 25=75 in²