Verified answer

100x = 15,555..

10x = 1,555..

90x = 14

x = 14/90 = 7/45

100y = 15,151515..

y = 0,151515..

99y = 15

y = 15/99 = 5/33

z = 3/4

(x/2y) - z = ( (7/45)/(10/33) ) - 3/4 =

(7/45)*(33/10) - 3/4 =

(7*33/450) - 3/4 = 77/150 - 3/4 = (4*77 - 3*150)/600 = (-142)/600 = -71/300

pronto