Answer:
x = 6
a = 18 ft
b = 36 ft
General Formulas and Concepts:
Pre-Algebra
- Order of Operations: BPEMDAS
 
Algebra I
- Factoring/Expanding
 - Solving quadratics
 
Trigonometry
- Pythagorean Theorem: a² + b² = c²
 
Explanation:
Step 1: Define
Given: Right triangle
a = 3x
b = 6x
c = 40
Step 2: Solve for x
- Substitute: (3x)² + (6x)² = 40²
 - Evaluate: 9x² + 36x² = 1600
 - Combine like terms: 45x² = 1600
 - Isolate x term: x² = 320/9
 - Isolate x: x = (±8√5)/3
 - Evaluate: x = ±5.96285
 
Since it is not a quadrant triangle, we must use the positive value for x.
Step 3: Find legs
Leg a
- Define: 3x
 - Substitute: 3(5.96285)
 - Multiply: 17.8885
 - Round: 18
 
Leg b
- Define: 6x
 - Substitute: 6(5.96285)
 - Multiply: 35.7771
 - Round: 36