Which describes the type of sequence in 99, 89.9, 78.8, 68.7, . . . ?
a) neither geometric nor arithmetic
b) geometric
c) arithmetic
d) both arithmetic and geometric
( tell me why you picked your answer)

Step-by-step explanation:

The is neither geometric nor arithmetic. The differences have to be the same.

99 - 89.9 = 9.1

89.9 - 78.8 = 11.1

78.8 - 68.7 = 10.1

b. an equilateral triangle inscribed in a circle

step-by-step explanation:

we are given the figure of two circles having a triangle inside.

now, we know that,

"when a figure is lying inside an another figure, then the outside figure is known as circumscribed figure and the figure lying inside is referred to as the inscribed figure".

as we see that, the circles are containing the triangle completely.

thus, the circles are the circumscribed figures and the triangle is the inscribed figure.

hence, we get, 'an equilateral triangle is inscribed in a circle'.

15

step-by-step explanation:

we are given the following expression and we are to solve it and find the product:

-13 × (-5)

solving the given expression in the standard order of solving a mathematical expression, beginning with the opening of brackets and then multiplying the terms and changing their signs.

-3 × -5 = 15 (answer is positive because when negative is multiplied with negative, it gives a positive answer)