Hello, mbruiz1!

The base material for a certain roadbed is 80% crushed rock when measured by weight.

How many tons of this material must be mixed with another material containing 30% crushed rock

to make 150 tons of material that is 40% crushed rock?

Let = tons of 80% material.

This contains tons of crushed rock.

Let = tons of 30% material.

This contains: tons of crushed rock.

The mixture will contain: tons of crushed rock.

But we know that the mixture will be 150 tons which is 40% crushed rock.

. . It will contain: tons of crushed rock.

We just described the final amount of crushed rock intwo.ways

There is our equaton! . . .

Got it?