As this rectangle has it's sides parallel to x axis and y axis 
 it is easy to find the length of it's sides by counting the number of blocks on each sides.
Let us first find co ordinates of all four points 
 we would calculate them left and right and up down direction from the origian ( the cross point of x and y axis ) 
A : it is 2 unit left 2 unit up ( -2 , +2 )
B is 5 unit right 2 unit up ( +5 ,+2)
C is 5 unit right 2 unit down ( +5,-2)
D is 2 unit left 2 unit down ( -2,-2)
Let us now find the distance AB : A is 2 unit left B is 5 unit right so length AB= 2+5 = 7 
Let us now find distance AD : A is 2 unit up and D is 2 unit down 
 so length AD= 2+2= 4
Answer should be 7 x 4 units 
 
        
                    
             
        
        
        
money going out (20.38+11.48+19.50) =51.36
balance - out = new balance
65.40-51.36 =
14.04
new balance =  14.04
 
        
             
        
        
        
The exponent of a number says how many times to use the number in a multiplication.
For Example, In 8² , the 2 is the number of times 8 has to be multiplied. In this case It has to multiplied by itself 2 times, 8x8 = 64 so 8² = 64.
Another example is 9³ since the number above is 3 we have to multiply 9 three times, 9x9x9 = 729 which means 9³ = 729.
Hope this helps