Determinar si cada par ordenado es una solución de 7x + 4y = –23.

Draw the triangle shown below to illustrate the problem.
Given:
a=25 ft, ∠B=65°, ∠C=38°.

Because angles in a triangle sum to 180°, therefore
∠A = 180 - 65 - 38 = 77°.

Apply the Law of Sines to find b and c.
b/sin(B) = a/sin(A)
b/sn(65°) = 25/sin(77°)
b = [sin(65)/sin(77)]*25 = 23.254 ft

c/sin(C) = a/sin(A)
c/sin(38) = 25/sin(77)
c = [sin(38)/sin(77)]*25 = 15.796 ft

The length of stone work required is
a + b + c
= 25 + 23.254 + 15.796
= 64.05 ft

64 ft (nearest integer).