(3/8 + 4 1/2)*240= 1170
1)) 3/8+ 4 1/2= 3/8+ (4•2+1)/2=
3/8+ 9/2= 3/8+ (9•4)/(2•4)=
3/8+ 36/8= 39/8
2)) 39/8• 240=
Сокращаем 8 и 240 на 8.
39/1• 30= 39•30= 1170.
В десятичных
(3/8 + 4 1/2)*240=1170
3/8= (3•125)/(8•125)= 375/1000=0,375
4 1/2= 4 (1•5)/(2•5)= 4 5/10= 4,5
1)) 0,375+4,5= 4,875
2))4,875•240= 1170.