If two bottles of fertilizer are needed for 42 feet perimeter, for 105perimeters, the number of fertilizers needed can be gotten using the law of equality as shown below;
2bottles = 42 feet perimeters
x bottles = 105feet perimeters
Cross multiplying to get the number of bottles 'x' we will have;
x bottles × 42feet perimeter = 2bottles × 105feet perimeter
x bottles = 2bottles×105ft perimeter/42ft perimeters