2a(5a-2) +3a(2a+6) + 8 = a(4a+1) + 2a(6a-4) + 50
Open the brackets
10a^2 - 4a + 6a^2 + 18a + 8 = 4a^2 + a + 12a^2 - 8a + 50
Collect like terms
10a^2 +6a^2 - 4a^2 - 12^2 + 18a + 8a - a = 50 -8
16a^2 - 16a^2 + 26a - a = 42
26a - a = 42
25a = 42
Divide both sides by 25
25a/25 = 42/25
a = 1.68