# David charges $15 plus$5.50 per hour to mow lawns. Ari charges $12 plus$6.25 per hour to mow lawns. In what situations is Ari's charge greater than or equal to David's charge?

David charges $15 plus$5.50 per hour to mow lawns. Ari charges $12 plus$6.25 per hour to mow lawns. In what situations is Ari's charge greater than or equal to David's charge?
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Jovanni Salinas
Let x be the number of hours of lawn mowing for which Ari's charge greater than or equal to David's charge. Then $12+6.25x\ge 15+5.5x$ or, $6.25x-5.5x\ge 15-12$ or, $0.75x\ge 3$ or, $\frac{3x}{4}\ge 3$. Now, on multiplying both the sides by $\frac{4}{3}$ , we get $x\ge 4$. Thus, if the lawn mowing hours are 4 or more, then Ari's charge is greater than or equal to David's charge