a
\(230+\left[16+\left(y-5\right)\right]=315\cdot1\)
\(230+\left[16+\left(y-5\right)\right]=315\)
\(16+\left(y-5\right)=315-230\)
\(16+\left(y-5\right)=85\)
\(y-5=85-16\)
\(y-5=69\)
\(y=69+5\)
\(y=74\)
b
\(707:\left[\left(2^y-5\right)+74\right]=16-9\)
\(707:\left[\left(2^y-5\right)+74\right]=7\)
\(\left(2^y-5\right)+74=707:7\)
\(\left(2^y-5\right)+74=101\)
\(2^y-5=101-74\)
\(2^y-5=27\)
\(2^y=27+5\)
\(2^y=32\)
\(2^y=2^5\)
\(\Rightarrow y=5\)