By just changing the x and numbers you can solve it:
-4x=-8 => x=2
a) This part is already complete I think..
b) This is a cuboid and lateral surface area of cuboid is: 2(lb +bh + hl)
= 2( 10 × 3 + 3 × 7 + 7 × 10)
= 2(30 + 21 + 70)
= 2 × 121 = 242 cm²
Now, the area of top & bottom: lb
= 2 × 10 × 3
= 60 cm²
Neglecting the top & bottom surface area of cuboid:
= 242 - 60
= 180 cm²
c) The total surface area us 242.. I have already done that part above...
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If i have done something wrong.. please lemme know :)
V or x is something so if you add 9 to get 8 then you must subtract 9 from 8 to get -1 which would be your answer