25 decresed by the product of number and 3

25-3x

Step-by-step explanation:

We can substitute X in for the number that we don't know.  Which makes "product of number and 3" equal to 3x and 25 decreased by that is 25-3x

I hope this helps and please don't hesitate to ask if there is anything still unclear!

give more details

step-by-step explanation:

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: