Question 802061
-7 - 6a + 5a = 3a - 5a
-7 - a = - 2a
-7 + 7 + 2a - a = -2a + 2a + 7
a = 7

check:
-7 - 6(7) + 5(7) = 3(7) - 5(7)
-7 - 42 + 35 = 21 - 35
-49 + 35 = - 14
-14 = -14