36v - 12 = 12 .....add 12 to both sides
36v - 12 + 12 = 12 + 12...simplify
36v = 24...divide both sides by 36
(36/36)v = 24/36
v = 2/3 <===
The simplifying of the expression will be -12a+102
Distribution
(a)(b+c)
ab+ac
applying that to your problem
(a-3)(a-8)
distribute (a-3)
(a-3)(a) +(a-3)(-8)
distribute again
aa-3a +(-8a) +24
add up like terms
3 tests at 75% each = 3 x 75 = 225 total points
First two tests = 79 + 84 = 163
Third test needs to be at least: 225 - 163 = 62%
So any score less than 62 would get you into trouble.