1)(3/14+5/21x)÷3/7=3 1/4
( 3/14 + 5/21х ) : 3/7 = 3 1/4 3/14 + 5/21х = 3 1/4 • 3/7 3 1/4 • 3/7 = 13/4 • 3/7 = 39/28 3/14 + 5/21х = 39/28 5/21х = 39/28 - 3/14 5/21х = 39/28 - 6/28 5/21х = 33/28 Х = 33/28 : 5/21 Х = 99/20 Х = 4,95