The sum of the first 7 terms of the geometric series is 15.180
<h3>Sum of geometric series</h3>
The formula for calculating the sum of geometric series is expressed according to the formula. below;
GM = a(1-r^n)/1-r
where
r is the common ratio
n is the number of terms
a is the first term
Given the following parameters from the sequence
a = 1/36
r = -3
n = 7
Substitute
S = (1/36)(1-(-3)^7)/1+3
S = 1/36(1-2187)/4
S = 15.180
Hence the sum of the first 7 terms of the geometric series is 15.180
Learn more on sum of geometric series here: brainly.com/question/24221513
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g(x) is the inverse of f(x)
A is aldult tickets
b is child tickets
b = 2/3 a
7a + 12b = 90
7a + 12 x 2/3 a = 90
7a + 8a = 90
15a = 90
a = 6; b = 4
