Question

How do you write the equation if Z is inversely proportional to the sum of x and y and the sum of x and y is 10 when Z is 4?

Answer 1

If `Z` is inversely proportional to `(x+y)`
then
`color(white)("XXXX")` `Z(x+y) = c` for some constant `c`

If `Z=4` and `(x+y) = 10` is a solution to this relation
then
`color(white)("XXXX")` `4(10) =c rarr c=40`

and the equation is
`color(white)("XXXX")` `Z(x+y) = 40`