First you need to find the difference of the two numbers and then add the difference to the other side.
Topping:
1-1/2=0.5 that means you have to add 0.5 to the other side as well. 1/4+0.5=3/4 or 0.75.
2-3/4 =1.25 so add 1.25 to the other side 1+1.25=9/4
10-9/4=7.75 so add 7.75 to the other side
2+7.75=39/4
13.5-39/4= 3.75 so add 3.75 to the other side
10+3.75= 55/4
50-55/4= 36.25 so add 36.25 to the other side
13.5+36.25=199/4
70-50=20 so add 20 to the other side
199/4+20=279/4
Filling: solve by adding to the other side just as before.
1-3/4=0.25 so 1/2+0.25=3/4
3-1=2 so 3/4+2=11/4
10-3=7 so 11/4+7=39/4
6-39/4= -3.75 so 10+(-3.75)=25/4
50-25/4= 43.75 so 6+43.75=199/4
50-199/4=0.25 so 50+0.25=201/4
It should look like this: