Answer:
 the same as multiplying them, except you're doing the opposite: subtracting where you would have added and dividing where you would have multiplied. If the bases are the same, subtract the exponents. Remember to flip the exponent and make it positive, if needed.
Step-by-step explanation:
 
        
                    
             
        
        
        
54=.9x Solve for x. x=54/.9=60
        
                    
             
        
        
        
The sup is 20 cm in total in square it is route 20 which is 10x2 so if its 1.50 dhs per sqm it will be 3 x 10 which is 30 dhs 
So 30 x 4 is 120 please mark as brainliest
        
                    
             
        
        
        
15. -(-7y + 12) = 7y - 12
16. 1/a = 16/18
      cross multiply
      16a = 18
      a = 18/16 = 9/8
17. 8x - 12 = 4x + 24
      8x - 4x = 24 + 12
      4x = 36
      x = 36/4
      x = 9
18. -6b > 42           4b > -4
       b < 42/-6          b > -4/4
       b < - 7              b > -1
so b < -7 and b > -1
19. 6 more then the product of 8 and n
      6 + 8n
20. 45 = 3b + 69
      45 - 69 = 3b
      -24 = 3b
      -24/3 = b
      -8 = b
        
                    
             
        
        
        
Answer:
3 Pounds of Coffee
Step-by-step explanation:
To find out how much she spent on the pounds of coffee, you would have to takeaway $65.37 away from the total of $90 which will give you $24.63, which is how much she has spent on the coffee. To find out how many pounds of coffee she bought, you would have to divide $24.63 by $8.21 giving you 3, which is how many pounds of coffee Teresa bought.
Much appreciated if this is marked as brainliest :)