All the denominators are positive but different, so express the rational numbers with the LCM of their denominators as the common denominator and then add.
LCM of 6, 4, 8 and 3 = 24
6−11+4−3+85+3−7=24(−11)×4+(−3)×6+5×3+(−7)×8=24−44−18+15−56=2415−118=24−103=−4247
Hence, 6−11+4−3+85+3−7=−4247.