How can i use 10+5x=74 as a scenario?

This is the slope intercept formula (y=mx+b) where:
74 = Y, or the dependent variable
x = the independent variable
5 = m, the coefficient, rate and slope line
10 = b, the y intercept

In this case, x = 12.8, so you'd want to use a valid scenario that 12.8 would make sense in. You wouldn't say, for instance:
An online t-shirt store charges $10 for shipping and $5 per t-shirt. How many people have to order a t-shirt in order for $74 worth to be sold?
Here, x = the people buying the t-shirts. So it wouldn't make sense if 12.8 people ordered t-shirts.

With that said, make the x value reasonable by using things such as measurement units or money.

I hope this helps but if you want me to provide you with a scenario, just ask me.

D.