c. \( 345.2 \times A=34,520 \) \( A= \)

b. \( x^{2}+2 x=15 \)

Write an equation that expresses the following relationship. \[ d \text { varies directly with } w \text { and inversely with the square root of } p \] In your equation, use \( k \) as the constant of proportionality.

○39.5. а) \( \left\{\begin{array}{l}x-3 y=5, \\ 3 x+2 y=4 ;\end{array}\right. \) б) \( \left\{\begin{array}{l}3 x+y=1, \\ 2 x-5 y=-22 ;\end{array}\right. \) о39.6. а) \( \left\{\begin{array}{l}x+y=4, \\ 4 x-5 y=7 ;\end{array}\right. \) б) \( \left\{\begin{array}{l}x-y=6, \\ 5 x-2 y=-3 ;\end{array}\right. \) о39.7. а) \( \left\{\begin{array}{l}40 x+3 y=-10, \\ 20 x-7 y=-5 ;\end{array}\right. \) б) \( \left\{\begin{array}{l}5 x+2 y=1, \\ 15 x+3 y=3 ;\end{array}\right. \)

Write an equation that expresses the following relationship. \( p \) varies jointly. with \( d \) and the square root of \( u \) In your equation, use \( k \) as the constant of proportionality. \( \square=\square \quad \frac{\square}{\square} \)

d. \( 2 x^{2}+27=-21 x \)