Can someone help me with this problem? I'd be grateful.
The Everton College store paid 1532 for an order of 42 calculators. The store paid $8 ea. for science calculators. The others, all graphing calculators, cost the store $54 ea. How many of each type of calculators was ordered?
Thank-you for any help.

$1532 for 42 calculators

I assume that the store didn't mark up the price. Otherwise, the problem is unsolvable.

S = number of scientific calculators
G = number of graphing calculators

S + G = 42
8S + 54G = 1532

You now have two (independent) equations and two unknowns. That is easily solvable.

This is how you(I would) figure if you don't know the formula.
You know most of the $1532 will need to be eaten up with the $54 calculators. 1532/54=28.370370..
so their can't be more than 28 $54 calculators, so you try 25X54=1350, so you try 17(42-25)X
8 and that equals 136.
1350+136=1486.
Now you know it is between 26 and 28 $54calculators.
The real problem is showing how you got this answer.