(a+b)*2 = 14.8
a=b+4.2
2b+4.2 = 7.4
2b = 3.2
b=1.6
a = b+4.2 = 1.6+4.2 = 5.8
ab = 1.6*5.8 = 9.28
18=2*3*3. 45=5*3*3. НОД(18;45)=3*3
1) 1/2 + 1/2+ 1/2
2) 2/3+2/3+2/3+2/3+2/3
3)7/10+7/10+7/10+7/10
4) 7/9+7/9+7/9+7/9+7/9+7/9
У=36-9•0
36-9•0=у
36-0=у
У=36