\(a.\)
\(\left(75.68+75.53\right):121\)
\(=\left[75\left(68+53\right):121\right]\)
\(=75.121:121\)
\(=75\)
\(b.\)
\(\left(47.69+47.75\right):141+53\)
\(=\left\{\left[47\left(69+75\right)\right]:141+53\right\}\)
\(=47.144:141+53\)
\(=48+53\)
\(=101\)
\(c.\)
\(\left(77.21-21.34+21.72\right):151-15\)
\(=21\left(77-34+72\right):151-15\)
\(=21.115:151-15\)
\(=\dfrac{2415}{151}-15\)
\(=\dfrac{150}{151}\)
1) \(\left(75.68+75.53\right):121\)
\(=\left[75\left(68+53\right)\right]:121\)
\(=\left(75.121\right):121\)
\(=75\)
2) \(\left(47.69+47.75\right):141+53\)
\(=\left[47\left(69+75\right)\right]:141+53\)
\(=\left(47.144\right):141+53\)
\(=6768:141+53\)
\(=47+53\)
\(=100\)
3) \(\left(77.21-21.34+21.72\right):151-15\)
\(=\left[21\left(77-34+72\right)\right]:151-15\)
\(=\left(21.115\right):151-15\)
\(=2415:151-15\)
\(\approx1\)
