Answer:
189 cm³
Explanation:
Volume of the object equals the volume of water increased. To find the volume of the water that increased, subtract the volume of water after increasing from the volume of water before increasing.
Volume of the rectangular container before water rise:
l = 9 cm ; w = 6 cm ; h = 7 cm

V₁ = 9 * 6 * 7
= 378 cm³
Volume of the container after water rise:
l = 9 cm ; w = 6 cm ; h = 7 + 3.5 = 10.5 cm
V₂ = 9 * 6 * 10.5
= 567 cm³
Volume of the water that increased = V₂ - V₁
= 567 - 378
= 189 cm³
Volume of the object = 189 cm³