15. a. Write an expression that uses both multiplication and addition (or subtraction) to describe the total fraction of Figure 5.7 that is shaded. (For example, 5/7·2/9+1/3 is an expression that uses both multiplication and addition.) Explain your reasoning. Then determine what fraction of the figure is shaded (in simplest form). You may assume that lengths appearing to be equal really are equal. b. Draw a figure in which you shade 1/4⋅1/3+3/5⋅1/3 of the figure. Explain your reasoning, then determine what fraction of the figure is shaded (in simplest form).

The picture is attach

first, we define the variables:

x: number of years after 1950

f (x): amount of vinyl sold.

then, with the variables defined, we have:

68594 vinyl records were sold in 1958 > f (8) = 68594

91299 vinyl records were sold in 1961 > f (11) = 91299

38720 vinyl records were sold in 1952 > f (2) = 38720

161743 vinyl records were sold in 1967 > f (17) = 161743

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step-by-step explanation:

a

step-by-step explanation:

the terms of a geometric sequence can be found by beginning with the first term and multiplying by the common ratio repeatedly. a recursive formula for a geometric sequence with common ratio r is given by an=ran−1 a n = r a n − 1 for n≥2 n ≥ 2 .

step-by-step explanation: