Since all parts of 2i(-3+7i) is in the denominator, you have to use an extra set of parentheses around the whole denominator. this is what you do
(5+i)(6−5i) / (2i(−3+7i))
= (30−25i+6i−5i^2) / (−6i+14i^2)
= (35−19i) / (−14−6i)
= (35−19i)(−7+3i) / (2(−7−3i)(−7+3i))
= (−245+105i+133i−57i^2) / (2(49−9i^2))
= (−188+238i) / (2(58))
= (−188+238i) / 116
= −47/29 + 119/58 iso that is how you do it