for the first one, another person already gave you the answer. For the second one, do y1-y2 over x1-x2. For the third one, move 8x to the other side, and 8 is the slope
So r+c=42
c=4+r
subsitute c=4+r for r in r+c=42
r+4+r=42
add like terms
2r+4=42
subtract 4 from both sides
2r=38
divide both sides by 2
r=19
rob=19
subsitute r=19 for r in c=4+r
c=19+4
carly=23
