The correct option is A −23
Re-arranging and grouping the numbers in pairs such that each group contains a pair of rational numbers with equal denominators, we have
−310+715+3−20+−910+1315+13−20
=(−310+−910)+(715+1315)+(3−20+13−20)
=(−310+−910)+(715+1315)+(−320+−1320)
=(−3)+(−9)10+7+1315+(−3)+(−13)20
=−1210+2015+−1620
=−65+43+−45
[Expressing each rational in lowest terms]
=(−65+−45)+43
=(−6)+(−4)5+43=−105+43
=−2+43=−6+43=−23