Answer
$135$
Work Step by Step
$\sum ^{7}_{i=3}\left( 5i+2\right) =5\sum ^{7}_{i=3}i+\sum ^{7}_{i=3}2=5\left( \sum ^{7}_{i=1}i-\sum ^{2}_{i=1}i\right) +\sum ^{5}_{i=1}2=5\left( \dfrac {7\times \left( 7+1\right) }{2}-\dfrac {2\times \left( 2+1\right) }{2}\right) +2\times 5=135$
