1) 15 4/7-4 3/8×(1 3/7-х)= 13 4/7
15 1/7×4 3/2(3/7-х)=13 4/7
15 1/7×4 3/2(3/7-х)= 52/7
15 1/7×2×3(3/7-х)=52/7
90/7×(3/7-х)=52/7
270/49-90/7х=52/7
270-630х=364
-630х=364-270
-630х=94
х=47/315
2)21/25×5/7-3/16х=11/20
3/5-3/16х=11/20
48-15х=44
-15х=44-48
-15х=-4
х=4/15