Answer:
90000 km 
Step-by-step explanation:
1 hour = 3600 sec
distance = speed x time 
               = 25 km/s x 3600 s
                = 90000 km
standard form = 9 x 10⁴
 
        
             
        
        
        
Hmm...this is difficult. The first thing I can think of is the relationship between age and time. 
        
                    
             
        
        
        
Answer:
x = 3
Step-by-step explanation:

 
        
             
        
        
        
Start by taking away 22.36 from each side so that you are left with 4.73c = 42.57
And then divide each side by 4.73 so you will get c = 9
        
                    
             
        
        
        
You are buying 2 items so let's use two different variables to represent each:
p = number of tubes of paint
b = number of disposable brushes
cost = price per item × number of items
Equations from information given:
4p + 0.50b = 20 ← from the first 2 sentences
2p = b  ← if there are twice as many brushes as paint tubes you need 2 times paint tubes to equal number of brushes
Solve the problem by using substitution... 1b equals 2p so replace b with that:
4p + 0.50(2p) = 20
4p + 1p = 20   ← 0.50 is half so half of 2p is 1p
5p = 20 ← combine like terms
p = 4   ← divide both sides of the equation by 5
Recall the equation 2p = b replace p with 4
2(4) = b 
8 = b
ANSWER:
You purchased 4 tubes of paint and 8 disposable brushes.