To find the total charge for a 2.7-mile ride using the formula \( c = 0.40m + 1.75 \), we can substitute \( m = 2.7 \) into the equation.
\[ c = 0.40(2.7) + 1.75 \]
First, we calculate \( 0.40 \times 2.7 \):
\[ 0.40 \times 2.7 = 1.08 \]
Next, we add that to the base fare of $1.75:
\[ c = 1.08 + 1.75 = 2.83 \]
Therefore, the total charge for a 2.7-mile ride is $2.83.