Answer:
9 books
Step-by-step explanation:
78=b(6)+c(4)
78=9(6)+6(4)
78=54+24
78=78-True
As per linear equation, Cindy bought 9 books online.
"A linear equation is an equation in which the highest power of the variable is always 1. It is also known as a one-degree equation.
The standard form of a linear equation in one variable is of the form Ax + B = 0. Here, x is a variable, A is a coefficient and B is constant. The standard form of a linear equation in two variables is of the form Ax + By = C. Here, x and y are variables, A and B are coefficients and C is a constant."
Given, Cindy was buying books ($6 each) and candles ($4 each).
She bought 15 items and spent $78.
Let, she bought 'x' books.
Therefore, she bought (15 - x) candles.
Now, the cost of the total 15 items is
= $[6x + 4(15 - x)]
= $[6x + 60 - 4x]
= $[2x + 60]
Therefore, 2x + 60 = 78
⇒ 2x = 78 - 60
⇒ 2x = 18
⇒ x = 9
Therefore, Cindy bought 9 books.
Learn more about a linear equations here: https://brainly.com/question/11897796
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