Answer:
30 lbs of boneless chicken must be purchased
Explanation:
using proportion to solve the problem
let x be the amount of boneless chicken to be bought, thn

=
( cross- multiply )
0.7x = 21 ( divide both sides by 0.7 )
x =
, that is
x = 30
30 lbs of boneless chicken must be purchased to yield 21 lbs of cooked chicken.