A currency is a system of money created and used by

simplify brackets

8 - 2a - 7 = a + 40

simplify 8 - 2a - 7 to -2a + 1

-2a + 1 = a + 40

add 2a to both sides

1 = a + 40 + 2a

simplify a + 40 + 2a to 3a + 40

1 = 3a + 40

subtract 40 from both sides

1 - 40 = 3a

simplify 1 - 40 o -39

-39 = 3a

divide both sides by 3

-39/3 = a

simplify 39/3 to 13

-13 = a

switch sides

a = -13

your answer would be letter d

the nets, boats and fishing poles are examples of determinants for catching fish. if a fisherman has a quality fishing net and fishing poles plus a high end fishing boat, then there is a big opportunity or possibility that he may catch more fish.

moreover, fish production is directly proportional to its determinants such as boat, net, fishing poles and bait. therefore, a good equipment is a determinant while fisherman’s effort is an input to his fishing skills and the output is the production made out of catching fish.