If Justin mowed 45% of her garden in 18 minutes, then we can set up a proportion to find how long it would take him to mow 100% of the garden:
45/100 = 18/x
where "x" is the unknown number of minutes it would take to mow 100% of the garden.
To solve for "x," we can use cross-multiplication:
45x = 100 * 18
Simplifying the right-hand side:
45x = 1800
Dividing both sides by 45:
x = 40
Therefore, it would take Justin 40 minutes to mow all of his garden at the same rate of 45% in 18 minutes.
To explain this, we used the fact that the amount of work done (mowing a certain percentage of the garden) is directly proportional to the time it takes to do that work. This means that if Justin mowed 45% of the garden in 18 minutes, he would take proportionally longer to mow the entire garden. The proportion we set up allows us to find the unknown amount of time it would take to mow the entire garden. Solving the proportion, we found that it would take Justin 40 minutes to mow all of his garden at the same rate he mowed the 45%.