See picture for details.

Say x = distance covered by the guy who went north. x will be 1.6 * 5.
y = distance covered by the guy who went west. y will be 1.2 * 5.

Notice that the distances form a right triangle, so the distance you're looking for is the hypotenuse of this triangle (say d).

d^2 = x^2 + y^2

d^2 = (1.6*5)^2 + (1.2*5)^2 = 5^2 (1.6^2 + 1.2*2) = 5^2 * 0.4^2 * (4^2 + 3^2) = 5^2 * 0.4^2 * 5^2

This means that d = 5*5*0.4 = 10.

Nice job Dana!!.

I got the same answer...

The key takeaway is to apply the d= rt formula to find the distance travelled by both the boats. Then use the Pythagoras theorem to find the length hypotenuse.