Z-1 3/4=2 7/12,m-7 1/9=2 5/36,n-10 7/12=3 1/6,r-6 1/7=1 5/14

Z-1 3/4=2 7/12
z-7/4=31/12
z=31/12+7/4
z=31/12+(7*3)/12
z=31/12+21/12
z=(31+21)/12
z=52/12
z=13/3
z= 4 1/3

m- 7 1/9=2 5/36
m-64/9=77/36
m=77/36+64/9
m=77/36+ (64*4)/36
m=77/36+256/36
m=(77+256)/36
m=333/36
m=111/12
m=9 3/12
m=9 1/4

n-10 7/12=3 1/6
n-127/12=19/6
n=19/6+127/12
n=(19*2)/12+127/12
n=38/12+127/12
n=(38+127)/12
n=165/12
n= 55/4
n=13 3/4

r- 6 1/7=1 5/14
r-43/7=19/14
r=19/14+43/7
r=19/14+(43*2)/14
r=19/14+86/14
r=(19+86)/14
r=105/14
r=15/2
r=7 1/2