Chris and Jim must replace a <em>total</em> quantity of 17 tyres.
<h3>What is the minimum number of tyres to be replaced?</h3>
In this problem we must use an inequality of the form f(x) ≥ a, where f(x) is the difference between the number of tyres replaced by Jim and the number of tyres replaced by Chris:
(25/20) · x - x ≥ 3
(5/20) · x ≥ 3
x ≥ 12
Then, the <em>minimum</em> number of tyres to be replaced is n = 15 + 12 = 17 tyres.
