Answer:
(8, -22)
Step-by-step explanation:
The tables each contain four (x,y) points of a straight line. You can see that for every increase of x by 2, y decreases by 8 in the first one (observe 26, 18, 10 2), and decreases by 6 in the second. 
If you continue the table with x=4, 6 and 8, you get y=-22 in both cases for x=8. That is the intersection, so the solution is (8,-22).
Added a graph. The equations are y=10-4x and y=2-3x respectively. Hope you understand a bit of this (brief) explanation.
 
        
             
        
        
        
18 cups, if you triple the amount without changing the percentage of strawberry, then the amount of strawberry yoghurt is also tripled
        
                    
             
        
        
        
It's a parallelogram so if one angle is 90 degrees they all will be because of transverse angles and all that good stuff.
So we're given the diagonal of a rectangle and one side and we're asked to find the other. The diagonal of a rectangle is the hypotenuse of the right triangle whose legs are the sides of the rectangle. So this is a Pythagorean Theorem question in disguise:




Answer: 140 cm
I don't recall seeing this Pythagorean Triple before.