Explain a Strategy You Could Use to Mentally Compute the Exact

Essay

Explain a strategy you could use to mentally compute the exact answer to the following.
A) $2 \frac { 3 } { 8 } + 5 \frac { 1 } { 4 } + 3 \frac { 7 } { 8 } + 2$

B) $2 \frac { 4 } { 5 } + 3 \frac { 1 } { 6 } + 5 \frac { 2 } { 3 } - 1.8$

C) $3 \frac { 1 } { 2 } - 2 \frac { 3 } { 8 }$