We will use the formula for the slope:
m = ( y2- y1 ) / ( x2 - x1 )
For PQ : m = ( 0 - 0 ) / ( a + c - 0 ) = 0
For RS : m = ( b - b ) / ( a - ( 2a + c )) = 0
Both slopes are m = 0, so PQ and RS are parallel to x - axis and at the same time parallel to each other ( PQ | | RS ). One pair of opposite sides is parallel.
The 3rd selection is appropriate.
.. 5b +1 = a = 3b +5
by the transitive property of equality,
.. 5b +1 = 3b +5
No because the 3 is the tens place. So its supposed to 3 ten blocks