subtract polynomials 7.8 X -3.4 Y plus Z and -9.2 X +4.8 Y -2.1 Z then place the answer in the proper location on the grid right answer in XYZ order and include the tenths place

Amerchant has coffee worth $60 a pound that she wishes to mix with 50 pounds of coffee worth $90 a pound to get a mixture that she will sell for $70 a pound. how many pounds of the & 60 coffee should be used?

Write two subtraction equations that are equivalent to 5 + 12 = 17.

Ihonestly have no clue if it's each or none.