At a local store, kelly and martin bought some notebooks and pencils. Kelly bought 4 notebooks and 25 pencils for 16.71. Martin bought 6 notebooks and 20 pencils for 21.74 what is the cost of 1 notebook and 5 pencils

Let n = cost of 1 notebook

Let p = cost of 1 pencil

Then,

3n + 4p = 8.5

5n + 8p = 14.5

You can solve for one variable in terms of the other and then substitute into the remaining equation.

3n + 4p = 8.5

+ 5n + 8p = 14.5

Multiply the top equation by - 2 so that the p-containing terms cancel each other out:

-2 (3n + 4p = 8.5)

+ 5n + 8p = 14.5

-n + 0 = - 2.5

So after dividing both sides by - 1, we see that n = $2.5. Plugging into the first equation gives p = $0.25.

3n + 4p = 8.5

5n + 8p = 14.5