Question

Suppose p varies directly as d, and p = 2 when d = 7. What is the value of d when p = 10?
A. d= 20/7
B. d= 7/5
C. d=35
D. d=15

Answer 1

\(\bf \begin{array}{cccllll}
\textit{something }&\textit{varies directly to }&\textit{something else}\\ \quad \\
\textit{something }&={\color{red}{ \textit{some value }}}&\textit{something else}\\ \quad \\
p&={\color{red}{ n}}&d&\implies p={\color{red}{ n}}d
\end{array}\\ \quad \\
p=2\qquad d=7\implies p={\color{red}{ n}}d\to 2={\color{red}{ n}}\cdot 7\)

solve for "n" to find the "constant of variation"
once you find "n", then plug it back in the equation

to find "d" when p=10, just set p = 10 and solve for "d"

Answer 2

15?