math
posted by Gav .
Amy bought some stationary from a bookstore. The total cost of 3 files A,B,C was $5.60 more than the total cost of 4staples. A cost $1.90 less than each of the other 2files. B cost $4.20 more than each staple. Find the cost of C

$X = Cost of B.
$X = Cost of C.
X !.90 = Cost of A.
X  4.20 = Cost of each staple.
X + X + (X1.90) = 4(X4.20) + 5.60,
3x  1.90 = 4x16.80 + 5.60,
3x  4x = 16.80 + 5.60 + 1.90 = 9.30,
x = 9.30,
X = $9.30. = Cost of B.
X = $9.30 = Cost of C.
X1.90 = 9.30  1.90 = $7.40=Cost of A.