78 intregi8/15=(78x15+8)/15=1178/15
12intregi 7/30=(12x30+7)/30=367/30
a+367/30=1178/15
a=1178/15-367/30
a=(1178x2-367)/30
a=1989/30=simplif cu 3=663/10=66 intregi 3/10
deci cealalta fractie este 66 intregi 3/10
2) x+2/5=11/15
x=11/15-2/5
x=(11-2x3)/15=5/15=simplif.cu 5=1/3
deci 1/3+2/5=11/15
3)
2intreg 1/2=5/2
1 intreg 3/8=11/8
5/2+11/8=(5x4+11)/8=31/8
5/2-11/8=(5x4-11)/8=9/8
31/8-9/8=22/8
deci cu 22/8 este mai mare suma fata de diferenta