Упростите выражение : 3 6 /7 x-7/9x+4 4 /63x; 2)4 2/9y+3

1) 3 6/7 x - 7/9x + 4 4/63x = x ((3 * 7 + 6)/7 - 7/9 + (4 * 63 + 4)/63) = x (27/7 - 7/9 + 256/63) =  x ((27 * 9)/63 - (7 * 7)/63 + 256/63) = x (243/63 - 49/63 + 256/63) = x (243 - 49 + 256)/63 = 450/63x = 150/21x = 7 1/7x.

2) 4 2/9y + 3 1/5y - 2 = y ((4 * 9 + 2)/9 + (3 * 5 + 1)/5) - 2 = y (38/9 + 16/5) - 2 = y ((38 * 5)/45 + (16 * 9)/45) - 2 = y (190/45 + 144/45) - 2 = 334/45y - 2 = 7 19/45y - 2.

3) 5 3/10x - 2 7/100x - 2/25x = x (53/10 - 207/100 - 2/25) = x (530/100 - 207/100 - 8/100) = x (530 - 207 - 8)/100 = 315/100x = 3.15x.

4) 5y - 4 3/8y + 4/5y = y (5 - (4 * 8 + 4)/8 + 4/5) = y (5 - 36/8 + 4/5) = y ((5 * 40)/40 - (36 * 5)/40 + (4 * 8)/40) = y (200/40 - 180/40 + 32/40) = y (200 - 180 + 32)/40 = 52/40y = 1.3y.