#### Answer

a = $\frac{3}{5}$b - 7

#### Work Step by Step

the answer is a = $\frac{3}{5}$b - 7 because the question states that a equals 7 less than the three fifths of b. So to write the function you would multiply 'b' by $\frac{3}{5}$ since it is three fifths of 'b' which means that you have to multiply 'b' by $\frac{3}{5}$ and thus it is $\frac{3}{5}$b. Also you have to subtract 7 from $\frac{3}{5}$b because 'a' is 7 less than three fifths of b.
Therefore the function is a = $\frac{3}{5}$b - 7