A birdwatcher on a cliff saw an eagle 70 feet above him. Earlier, he had spotted the eagle 30 feet above him.
Which integer represents the eagle's change in altitude?

Areflection of shape i across the y-axis, followed by a , and then a translation left 6 units and down 4 units confirms congruence between shape i and shape ii. alternatively, a of shape ii about the origin, followed by a reflection across the y-axis, and then a translation right 4 units and up 6 units confirms congruence between shape ii and shape i.