3. The ratio of girls to boys in the seventh grade is \( 5: 7 \). How many boys are seventh grade if there are 40 girls?

Solve the equation. (Enter your answers as a comma-separated list. If there is no solution, enter NO SOLUTION.) \[ 6 w+7 w^{1 / 2}-20=0 \] \( w=\square \)

Tunjukkan bahawa ungkapan \( 2^{n+1}+2^{n}+2^{n-1} \) boleh dibahagi tepat dengan 7 bark semua integer positif bagi \( n \). Show that the expression \( 2^{n+1}+2^{n}+2^{n-1} \) is divisible by 7 for all positive integ of \( n \). [ 2 markah/mar

6) \( 30 \% \) of \( 600=\ldots(1.8,18,180,1800) \)

a) \( x^{2}+5 x+1 \)

\( \lim _ { x \rightarrow + \infty } ( x ^ { 4 } + 3 x ^ { 2 } - x ( x ^ { 2 } - 1 ) \sqrt { x ^ { 2 } + 9 } ) = \)