Question

me ajudem com estas contas 
 5x+3x=168
4x+3=x+12
3x-5=x+15
2(x-1)=26
2(x+2)=36
15-5(x+5)=60

Answer 1

a) 5x + 3x = 168
8x = 168
x = 168/8
x = 21

b) 4x + 3 = x + 12
4x - x = 12 - 3
3x = 9
x = 9/3
x = 3

c) 3x - 5 = x + 15
3x - x = 15 + 5
2x = 20
x = 20/2
x = 10

d) 2 (x - 1) = 26
2x - 2 = 26
2x = 26 + 2
2x = 28
x = 28/2
x = 14

e) 2 (x + 2) = 36
2x + 4 = 36
2x = 36 - 4
2x = 32
x = 32/2
x = 16

f) 15 - 5( x + 5) = 60
15 - 5x - 25 = 60
- 5x = 60 + 25 - 15
- 5x = 70 (-1)
5x = - 70
x = -70/5
x = - 14

Answer 2

a) $5x+3x=168$

$8x=168$

$x=\dfrac{168}{8}~~\Rightarrow~~x=21$.


b) $4x+3=x+12$

$4x-x=12-3$

$3x=9$

$x=\dfrac{9}{3}~~\Rightarrow~~x=3$


c) $3x-5=x+15$

$3x-x=15+5$

$2x=20$

$x=\dfrac{20}{2}~~\Rightarrow~~x=10$


d) $2(x-1)=26$

$2x-2=26$

$2x=28$

$x=14$


e) $2(x+2)=36$

$x+2=18$

$x=16$


f) $15-5(x+5)=60$

$15-5x-25=60$

$-5x-10=60$

$-5x=70$

$x=-14$