You need to know these two formulas:

For example,

Answer:
15
Step-by-step explanation:
10 is 5 less than fifteen.
Sorry if its wrong
Answer:
390 ft²
Step-by-step explanation:
The longer base of a trapezoid is 8 ft. The longer base of a similar trapezoid is 13 ft. The area of the smaller trapezoid is 240 ft² What is the area of the larger trapezoid?
We solve the above question using proportion
(Longer base/Area of trapezoid) smaller trapezoid = (Longer base/Area of trapezoid) bigger trapezoid
Let the the Area of the bigger trapezoid = x
Hence,
= 8ft/240ft = 13ft/x ft
Cross Multiply
8ft × x = 240ft × 13ft
x = 240ft² × 12 ft/8 ft
x = 390 ft²
Identify the angle variable to use.
Write an equation.
Solve the equation for the variable.
Find the unknown angle measure.