Malco weighs 42 more pounds than peter the sum of their weights is 286 pounds how much does peter way

So, let's establish some variables:

P = Peter
M = Malco = P + 42

Now let us establish an equation to find for P:
268 = P + P + 42
268 = 2P + 42
268 - 42 = 2P
226 = 2P
226 / 2 = P
113 = P

Now to find for M:
P + M = 268
113 + M = 268
M = 268 - 113
M = 155

Peter = 113 pounds
Malco = 155 pounds

Hope it helped,

BiologiaMagister