a/2=4/5b
a) 5ab=8
15ab=5abx3=8x3=24
15ab-2.8 =24-2,8=21,20
b) 1, (7)= 1 intreg si 7/9=(9x1+7)/9=16/9
5ab=8
ab=8/5
3ab=3x8/5=24/5
2/3ab=2/24/5=10/24=5/12
5/12-16/9=(3x10-8x16)/72=(30-128)/72=-98/72=49/36
c) ab=8/5
1intreg si 1/25=(25x1+1)/25=26/25
8/5+26/25=(8x5+26)/25=(40+26)/25=66/25