Final answer:
In an isosceles triangle with angles B and C congruent, and with m∠A equal to 40°, the equation to find x is 40° + 2(3x + 1)° = 180°. Solving this equation yields x = 23°, which corresponds to option b.
Step-by-step explanation:
Since ΔABC is an isosceles triangle and angles B and C are congruent, m∠B = m∠C. Given that m∠A = 40°, we can set up an equation to find x since the sum of all angles in a triangle equals 180°.
Equation: 40° + (3x + 1)° + (3x + 1)° = 180°
Combining like terms:
40° + 2(3x + 1)° = 180°
40° + 6x + 2° = 180°
6x + 42° = 180°
6x = 180° - 42°
6x = 138°
x = 23°
Therefore, the value of x is 23°, which corresponds to option b.