By interchanging the given two signs, which of the following equations will NOT be correct?
$$\times$$ and -
I. $$17 - 21 + 86 \div 2 \times 13 = 387$$
II. $$10 + 63 - 12 \times 259 \div 7 = 739$$

I.  $$17 - 21 + 86 \div 2 \times 13 = 387$$

By interchanging $$\times$$ and -, a new equation is formed which is given below.

$$17 \times 21 + 86 \div 2 - 13 = 387$$

$$357 + 43 - 13 = 387$$

357 + 30 = 387

387 = 387

The given equation is satisfied. So this is the correct equation.

II. $$10 + 63 - 12 \times 259 \div 7 = 739$$

By interchanging $$\times$$ and -, a new equation is formed which is given below.

$$10 + 63 \times 12 - 259 \div 7 = 739$$

$$10 + 756 - 37 = 739$$

$$766 - 37 = 739$$

$$729\ne739$$

The given equation is not satisfied. So this is not the correct equation.