answer: b = 9
rearrange so we can subtract 16 by 7
16 - 7 = 9
substituting 9 for b and making sure it's correct.
16 - 9 = 7
two dogs and three ducks
dogs have four legs and ducks have two, to find the answer, you add the number to get your answer.
in this case, two dogs would make a total of 8 legs and three ducks would make a total of 6 legs. adding 8 and 6 together, you get 14.
3 * x + 8 = 31