The ratio 7 : 2 means 7 units for A and 2 units for B.<br><br>
[[model:questions/solutions/q7589.png]]<br><br>
&bull; 2 units → 40 kg<br>
&bull; 1 unit → 40 ÷ 2 = 20 kg<br>
&bull; A&rsquo;s mass = 7 units = 7 × 20 = 140 kg<br>
&bull; Times heavier = \frac{7}{2} = 3.5<br>
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A&rsquo;s mass is 140 kg; A is 3.5 times heavier than B.<br>
Check: 140 ÷ 40 = 3.5. ✓