Answer:Mark Is 9 years old; Christine is 5 years old 
Step-by-step explanation:
 Present age 
 LET  mark age be x
 Christine be x-4 yrs
In 3 yrs Time 
Mark will be x+3 yrs old
Christine  will be  (x -4 +3) = x-1 years old 
Also, In 3 years time 
Christine  = 2/3 Mark
such that 
   x-1 = 2/3(x+3)
   x -1= 2x+6 / 3
     3x  -3= 2x+6
       3X--2X = 6+3
          =X=9
Mark Is 9 years old 
Christine is   x -4 = 9-4=5 years old 
 
        
             
        
        
        
Answer:
No Solution
Step-by-step explanation:
There are no values of  b
 that make the equation true.
No solution
 
        
             
        
        
        
First, we need to add 2/6 and 2/5. 
2/6 can be simplified to 1/3
We need to have 1/3 and 2/5 have the same denominator. 3 and 5's LCM (least common multiply) is 15. 
Multiply both the numerator and denominator of 1/3 by 5. This equals 5/15. 
Multiply both the numerator and denominator of 2/5 by 3. This equals 6/15. 
5/15 plus 6/15 is 11/15. This means that Jack's 6000 dollars is 4/15.
Let's say that x is the total amount invested by all three. 
6000/x would equal 4/15. 
Solve this by multiply 6000 by 15 and 4 by x and making these two equal each other. 
90000 would equal 4x. Divide both sides by 4 to get x. 
90000 divided by 4 would be 22500. 
4/15 is the fraction by Jack 
22500 is the total amount invested by all 3
 
        
             
        
        
        
Focus on triangles DFC and DFE:
- They are both right triangles because DF is perpendicular to EC
 - DC=DE
 - DF is a common side
 
So, the two triangles are congruent. It follows that CF=FE, and in particular

And since x=3, the length of EF is

 
        
             
        
        
        
Answer:
the second one
Step-by-step explanation:
7 - (2m - 5)