<span>(3 * 3 * 3 - 3) * 3 = 72
</span><span>(33 - 3*3)*3 = 72
</span>
1/3x+1/4x+1/5x=1 19/75
х*( 1/3+1/4+1/5)=1 19/75
х*47/60=1 19/75
х=1 19/75 : 47/60
х=94/75*60/47
х=8/5
х= 1 3/5
Б)=3(5/12)+12(2/3)+4(1/9)=15/36+24/36+4/36=(15+24+4)/36=43/36=1 цел. 7/36
Х - неизвестный член пропорции
24х=12*60
24х=720
х=720:24
х=30