Question

c)[(15+76:x)×13+500]:20=38           d)2×(3x+2)-22=5×(x+1)+78   e)[5×(2×x+3)+4×(2×x+3)]:5=27          f)2×{27-2×[3×x-(35:5-2×3)]+3}:4=10

Answer 1

C)[(15+76:x)·13+500]:20=38
(15+76:x)·13+500=38 ·20
(15+76:x)·13+500=760
(15+76:x)·13=760-500
(15+76:x)·13=260
15+76:x=260:13
15+76:x=20
76:x=20-15
76:x=5
x=76:5
x=15,2


d)2·(3x+2)-22=5·(x+1)+78
6x+4-22=5x+5+78
6x-18=5x+83
6x-5x=83+18
x=101


e)[5·(2·x+3)+4·(2·x+3)]:5=27
(10x+15+8x+12):5=27
(18x+27):5=27
18x+27=27·5
18x+27=135
18x=135-27
18x=108
x=108:18
x=6


f)2·{27-2·[3·x-(35:5-2·3)]+3}:4=10
2·{27-2·[3·x-(7-6)]+3}:4=10
2·[27-2·(3·x-1)+3]:4=10
2·[27-2·(3·x-1)+3]=10·4
2·[27-2·(3·x-1)+3]=40
27-2·(3·x-1)+3=40:2
27-2·(3·x-1)+3=20
30-2·(3·x-1)=20
2·(3·x-1)=30-20
2·(3·x-1)=10
3·x-1=10:2
3·x-1=5
3·x=5+1
3·x=6

x=6:3
x=2

Answer 2

c)[(15+75:x)×13+500]:20=38 
(15+75:x)×13+500=38×20(15+76:x)×13+500=760(15+76:x)×13=760-500
(15+75:x)×13=26015+76:x=260:13
15+75:x=20
75:x=20-15
75:x=5
x=75:5
x=15