Mathematical problem "four mixed operations of fractional multiplication" What can be calculated simply should be calculated simply (1 / 2 minus 1 / 3 plus 1 / 4 minus 1 / 5 plus 1 / 6 minus 1 / 7) x210

Mathematical problem "four mixed operations of fractional multiplication" What can be calculated simply should be calculated simply (1 / 2 minus 1 / 3 plus 1 / 4 minus 1 / 5 plus 1 / 6 minus 1 / 7) x210

Equal to half x210 minus one third x210 plus one fourth x210 minus one fifth x210 plus one sixth x210 minus one seventh x210;
Equal to 105-70 + 52.5-42 + 35-30;
It's 50.5
(Law of multiplicative distribution)