Question

what will be the equation

Answer 1

let the age of sandeep is =x
and his father age is =y

now first equation...
sandeep father is thrice old as sandeep
so...
y=3x .......1

second equation
after 10 years he will be twice of sandeep age
so....
y+10=2(x+10)
y+10=2x+20
2x+20-10-y=0
2x-y+10=0 ..........2


so put eq 1 y value in eq 2 and solve....



thanks
mark brainlist if possible

Answer 2

$\bigg\dfrac{1}{sin\theta}\bigg$

$\dag\:\boxed{\tt{\eta=\dfrac{c}{v}=\dfrac{speed\:of\:light\:in\:vacuum}{speed\:of\:light\:in\:medium}}}†$

$\sf\theta{x}$