Can some one just need equation worth 15point

Explanation:

Let's say we're buying only 8 dollars of stuff. 8 dollars can only be formed, in this case, by 2 oyster shell grit bags, since they costs 4 dollars each.

Now, we already bought 2 oyster shell grit bags, now we have to buy sunflower seeds. Let's say we're buying only 20 dollars of sunflower seeds. 20 dollars can only be formed, in this case, by 4 sunflower seeds bags since they cost 5 dollars each.

Equation:

x will be the number of oyster shell grit bags and 6 - x will be the number of sunflower seeds bags.

4x + 5(6 - x) = 28 → we combine the price with the corresponding variables.

4x + 30 - 5x = 28

4x - 5x = 28 - 30

-1x = 28 - 30

-1x = -2

x = -2 / -1

x = 2

So, if x = 2, 6 - x = 6 - 2 which equals 4.

Hope it helped,

BioTeacher101