Can you help me solve these and tell me when to add, subtract or divide ???

Question

1)  Solve 18 = x over  -3.

2) Each week the average household reads 5 pounds of newspapers.You are recycling 50 pounds of newspapers. Which equation could be used to estimate the numbers of weeks during which your household reads the paper?

a.  50x = 5

b.  5x = 50

c.  5 + x = 50

d. 50 + x = 5

e.  50 - x = 5

 

3)  Solve the equation 8(2x - 1) - 5x = 25.

4)  Solve - 2 over 3(x + 2) = 12.

5)  Solve x + 3 = x - 6.

6)  Which equations are equivalent?

a.  2a - 6 = 5 + 9a    or  b.  5a = 11 + 12a   or  c.  -11 = 7a

 

7)  For which equation is m = 7 a solution?

a.  m - 5 = 3m - 18

b.  m - 5 = 3m - 19

c.   2m = 3m - 17

d  2m = -3m - 30

e.  2m + 1 = -3m - 30

 

Please help me, I just don't get this???? Can you explain when to multiply or divide to me. I'm just learning and I don't get this?  Thank you so very much!  :)

Answer 1

1) 18=x/(-3), x=-3×18=-54.

2) b (x is the number of weeks at 5 pounds per week)

3) 8(2x-1)-5x=25, 16x-8-5x=25, 11x=33, x=3.

4) -2/(3(x+2))=12, 3(x+2)/(-2)=1/12, 3(x+2)=-2/12=-⅙, 3x+6=-⅙, 3x=-6-⅙=-6⅙=-37/6, x=-37/18.

5) x+3=x-6 has no solution because it's a false statement: 3=-6 is false.

6) They're all equivalent.

7) b (19-5=3m-m, 14=2m, m=14/2=7).