А) 3 3/4 + 1 1/2 = 3 3/4 + 1 2/4 = 4 5/4 = 5 1/4
б) 2 5/6 - 1 5/12 = 2 10/12 - 1 5/12 = 1 5/12
в) 4 - 1 2/3 = 3 3/3 - 1 2/3 = 2 1/3
г) 3 2/7 - 6/7 = 2 9/7 - 6/7 = 2 3/7
д) 1 1/3 * 4 = 4/3 * 4 = 16/3 = 5 1/3
е) 3 1/4 * 2/5 = 13/4 * 2/5 = (13*1)/(2*5) = 13/10 = 1 3/10
ж) 2 1/4 : 3 = 9/4 * 1/3 = (3*1)/(4*1) = 3/4
з) 20 : 2 1/2 = 20 : 5/2 = 20 * 2/5 = 4 * 2 = 8