Question

carly and rob combined their dvd collections. now they have 42 dvds in all carly had 4 more dvds than rob. how many dvds did carly have?

Answer 1

The best thing to do here is to subtract the difference, which is 4. 42-4=38. You've then got to split them in half, 38/2=19. Therefore, Rob had 19 and Carly had 23 Hope this helps :)

Answer 2

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