A=71 38/45-(43 8/45 + 1 17/57)
=( 71 38/45-43 8/45 )+ 1 17/57
= 28 2/3 + 1 17/57
= 29 55/57
\(A=71\frac{38}{45}-\left(43\frac{8}{45}+1\frac{17}{57}\right)\)
\(A=\frac{3233}{45}-\left(\frac{1943}{45}+\frac{74}{57}\right)\)
\(A=\frac{3233}{45}-\frac{1943}{45}-\frac{74}{57}\)
\(A=\frac{86}{3}-\frac{74}{57}=\frac{520}{19}\)