Given: r ∥ s Prove: m r = m s Two parallel lines passing the vertices with red line r at points (c, d) at (2, 10) and (0, b) at (0, 6) and blue line s intercepts (c, 0) at (2, 0) and (0, a) at (0, minus 4) Statements Reasons 1. r ∥ s given 2. m r = d − b c − 0 = d − b c m s = 0 − a c − 0 = - a c application of the slope formula 3. distance from ( 0 , b ) to ( 0 , a ) equals the distance from ( c , d ) to ( c , 0 ) definition of parallel lines 4. ? application of the distance formula 5. m r = ( b − a ) − b c substitution property of equality 6. m r = - a c inverse property of addition 7. m r = m s substitution property of equality The table and corresponding image show the proof of the relationship between the slopes of two parallel lines. What is the missing statement in step 4? A. c − d = b − a B. d − 0 = b − a C. b − c = d − a D. c − 0 = a − b