A=1/2 b*h
So substitute it in 1/2*1/2*4
1/2*1/2= 1/4
1/4*4= 4/4= 1 so the entrance is 1 foot tall
garden: Area = 7 x 4 = 28
plants: Area = 1 x 1 x 30 plants = 30
30 - 28 = 2
Answer: 2 plants
$0.86. You either divide by 10 manually, or use the powers of 10.