(4/5+1/6)×(21 2/3-15 5/9)×45/58-1/4=

(4/5+1/6)×(21 2/3-15 5/9)×45/58-1/4= 29/30( 7*2-5  5/3)* 45/58-1/41/30* 17/3*45/2-1/41/2*17*1/2-1/417/4-1/4 = 4