Factor the polynomial
16z2 + 25

16z^2 + 25

This polynomial is already in lowest terms.

Cannot be factored.

This happens with certain polynomials.

Step-by-step explanation:

Let the mass of the metal be x

From the question

5/9 of the metal is 7kg

That's

Multiply through by 9

We have

5x = 7 × 9

5x = 63

Divide both sides by 5

We have the final answer as

x = 12.6 kg

Hope this helps you