the everton college store paid $1553 for an order of 42 calculators. the store paid $9 for each scientific calculator. the others, all graphing calculators, cost the store $56 each. how many of each trupe of calculator was ordered?

Question

the store ordered:
how many scientfic calculators?

graphing calculators?

Answer 1

Let
S = number of scientific calculators

"an order of 42 calculators."
42-S = number of graphing calculators.

"the store paid $9 for each scientific calculator... graphing calculators, cost the store $56 each"

Total cost
= $9*S + $56*(42-S)
Since the total cost is $1553, solve for S in
$1553 = $9*S + $56*(42-S)