Answer:
320 square feet
Step-by-step explanation:
To find the space you can cover with 1-pound bag of fertilizer, we need to divide 1,200 by 3.75. It makes things easier to think of how 3.75 ÷ 3.75 = 1. Anyways, 1,200 ÷ 3.75 = 320. Therefore, you can cover 320 square feet with a 1-pound bag of fertilizer.
Well the area of a trapezoid is defined by the following formula:
A =

where b₁ and b₂ are the bases of the trapezoid and h is the height of the trapezoid.
Let's plug in what we know into this formula:
h = 7 the perpendicular distance between the two bases
b₁ = 15 the shorter parallel side
b₂ = 25 the longer parallel side made up of 4 + 15 + 6
so, A =

This is in square units of measure of course, so 140 in²