Dogs are 3 of the 7 equal units, and those 3 units are 21 dogs.<br><br>[[model:questions/solutions/q3409.png]]<br><br>• 3 units → 21 dogs<br>• 1 unit → 21 ÷ 3 = 7<br>• Total → 7 units = 7 × 7 = 49<br><br>The pet shop has 49 animals.<br>Check: dogs → $$\frac{3}{7}$$ of 49 = 21. ✓