Total number of pounds=15x number of bags
#9
since LJ = LK + KJ, replace the letters with the corresponding equations. You'd get:
LJ = (7x-10) + 28
LJ = 7x + 18
Do you need an integer or is that okay?^
Cut each sandwich into pieces of thirds
4 sandwiches x 3 pieces = 12 total pieces
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12 / 6 = 2
Everybody would get 2 pieces
You could say 8r+2 times s +4 or –5x2y4