Final answer:
The perimeter of Jackson's rectangular yard is 80 yards, calculated by summing twice the length (2 x 21 yards) and twice the width (2 x 19 yards).
Step-by-step explanation:
The perimeter of a rectangular yard is calculated by adding together the lengths of all four sides. Since Jackson's dad measured the two longer sides as 21 yards each and the two shorter sides as 19 yards each, you would calculate the perimeter by doing the following:
- Longer side 1: 21 yards
- Longer side 2: 21 yards
- Shorter side 1: 19 yards
- Shorter side 2: 19 yards
Adding these measurements together, the formula for the perimeter (P) is P = 2l + 2w, where l represents the length, and w represents the width of the yard. Therefore, P = 2(21 yards) + 2(19 yards) = 42 yards + 38 yards = 80 yards. So, the perimeter of the yard is 80 yards.