Simple calculation of 21 / 5 * 1 / 31 + 4 / 5 * 21 / 31

Simple calculation of 21 / 5 * 1 / 31 + 4 / 5 * 21 / 31

21/5×1/31+4/5×21/31
=21÷(5×31)+(4×21)÷(5×31)
=(21+4×21)÷(5×31)
=(5×21)÷(5×31)
=5×21÷5÷31
=21÷31
=21/31