Help please show work

7.) 18.8 square kilometers
1/2 • 4.7 x 8 = 18.8

8.) 40.96 square miles
6.4^2 = 40.96

9.) 7 square meters
1/2 • 4 • 3.5 = 7

10.) 36.4 square centimeters
(2.6 + 7.8) ÷ 2 x 7

11.) 22.8 square yards
6 • 3.8 = 22.8

12.) 30.6 square centimeters
5.1 • 6 = 30.6

Explanation:
FORMULAS FOR AREAS OF:
Triangle: 1/2 • base • height
Square: side^2
Parallelogram: base • height
Rectangle: Length • width
Trapezoid: (a + b) ÷ 2 x height
(a & b are the two bases)

hope this helps!