Question

The number of boys and girls in a class are in the ratio 7:5 . The number of boys is 8 more than the number of girls. What is the total class length?​

Answer 1

Answer:

total class length=68

Step-by-step explanation:

let the number of boys be 7x and girls be 5x

7x=8+5x

7x-5x=8

2x=8

x=8/2=4

number of boys = 7*4=28

number of girls=5*8=40

total class length=28+40=68

Answer 2

Step-by-step explanation:

$\sf Let \begin{cases}\sf\longrightarrow Number\: of \:girls=x \\ \sf\longrightarrow Number\:of\:boys=x+8\end{cases}$

ATQ,

$\\ \qquad\quad\sf\longmapsto \dfrac{x+8}{x}=\dfrac{7}{5}$

• Using cross multiplication

$\\ \qquad\quad\sf\longmapsto 5(x+8)=7x$

$\\ \qquad\quad\sf\longmapsto 7x=5x+40$

$\\ \qquad\quad\sf\longmapsto 7x-5x=40$

$\\ \qquad\quad\sf\longmapsto 2x=40$

$\\ \qquad\quad\sf\longmapsto x=\dfrac{40}{2}$

$\\ \qquad\quad\sf\longmapsto x=20$

$\sf We\:get \begin{cases}\sf\longrightarrow Number\: of \:girls=x=20 \\ \sf\longrightarrow Number\:of\:boys=x+8=20+8=28\end{cases}$

$\\ \qquad\quad\bf\longmapsto Total\:strength =28+20=48$