1) 1/40 + 3/8= 1/40 + 15/40 = 16/40 = 4/10
1/6 : 4/10 = 1/6 * 10/4 = 10/24 = 5/12
5/12 + 1/3= 5/12 + 4/12 = 9/12 = 3/4
1/4 *х = 3/4
х = 3/4 : 1/4 = 3
х = 3
2) 1/2 - 2/5 = 5/10 - 4/10 = 1/10
1/4 : 1/10 = 10/4 = 5/2
5/2 + 1/2 = 6/2 = 3
3/4*х = 3
х = 3:3/4 = 4
х = 4